Abstract:The LaCoO₃/LaMnO₃ bilayers epitaxial film grown on (100) SrTiO₃ substrates were obtained by a simple polymer assisted sol-gel deposition method. Growing a LaCoO₃ layer on the top of LaMnO₃ leads to the asymmetric interface coupling at the interface layer due to their difference in strucural symmetry, and reduces the ferromagnetic transition temperature caused by the asymmetric interface coupling effect from 262 K to 200 K. In addition, compared with the coercive field of isolated LaMnO₃ film, the coercive field observed in the bilayers is increased by ~500% due to a strong ferromagnetic Mn-O-Co double exchange interaction at the interface. The results demonstrate that the recombination of multilayer films with different properties provides a new way to design functional materials for fundamental studies or demanding applications.

Abstract:Thermodynamics of hydrogen absorption and phase transformations in Ti6Al4V alloy were investigated by pressure-composition (P-C) isotherm measurement at hydrogenation temperatures in the range of 823~1023 K. Results show that the hydrogen pressure is increased with increasing the hydrogen content when Ti6Al4V alloy is hydrogenated at different temperatures. Only one sloped pressure plateau occurs in each P-C isotherm during the hydrogenation treatment because of the existence of original β phase in Ti6Al4V alloy. According to Vant's Hoff law, the values of enthalpy and entropy of the pressure plateau region are -50.7±0.26 kJ/mol and -138.4±0.69 J·K^-1·mol^-1, respectively. The Sieverts constant increases firstly and then decreases gradually with increasing the hydrogenation temperature. The phase composition and phase transformation of Ti6Al4V alloy during the hydrogenation treatment were analyzed.

Abstract:FeCoCrNiZr_x (x=0.5, 0.75, 1) high-entropy alloys with different Zr contents were prepared by vacuum arc melting. The effects of Zr content on the microstructure, magnetic properties, and electrochemical corrosion properties of the alloys were studied. X-ray diffraction, scanning electron microscope, vibration sample magnetometer, and electrochemical workstation were used to study the magnetic property and electrochemical corrosion ability of FeCoCrNiZr_x alloys. Results show that FeCoCrNiZr_x alloy has typical eutectic structure, consisting of face-centered cubic solid solution and C15 Laves phase. With the increase of Zr content, the hardness of the alloy increases at first and then decreases. However, according to the synthesized static hysteresis curves, FeCoCrNiZr_0.5 alloy shows a mixture characteristic of paramagnetism and ferromagnetism, FeCoCrNiZr_0.75 alloy has paramagnetic behavior, and FeCoCrNiZr₁ alloy has typical ferromagnetism. Meanwhile, the FeCoCrNiZr_x alloy undergoes activation-passivation transition in 3.5wt% NaCl solution. When the content of Zr is 0.75at%, the polarization resistance of the alloy has the maximum impedance capacitance radius, and the corrosion resistance of the passive film is the strongest.

Abstract:Pt/Al₂O₃ catalysts were prepared by an excess impregnation method with Pt(NH₃)₂(NO₂)₂ as the precursor. Then they were calcined in four different atmospheres (H₂, O₂, NO, NH₃), and characterized by N₂ adsorption and desorption test, X-ray diffraction, H₂-temperature programmed reduction (TPR) test, CO pulse adsorption test, and CO in-situ diffuse reflectance infrared Fourier transform spectroscopy (CO in situ DRIFTS). Results show that Pt/Al₂O₃ catalyst calcined in 1vol% H₂/N₂ atmosphere exhibits the best catalytic oxidation performance for CO and C₃H₆, because of the generation of numerous small-sized and highly dispersed Pt nanoparticles caused by the reducing calcination atmosphere.

Abstract:A series of Ti-based bulk metallic glass composites (BMGCs) and a Ti-based bulk metallic glass were prepared by arc melting, and the effect of Be contents on the wear performance was investigated. The results show that the decrease in Be content in the composites increases the volume fraction of dendrites in BMGCs; the increase in the volume fraction of dendrites reduces the coefficient of friction, but increases the wear ratio slightly. All the worn surfaces show abrasive wear, and the size of wear debris is decreased with increasing the volume fraction of dendrites.

Abstract:Graphene nanoplatelets (GNPs) reinforced 7075Al nanocomposites were synthesized by pressure sintering method. A novel method for optimizing interfacial bonding through TiO₂ coated GNPs was proposed. The effects of TiO₂ coated GNPs on mechanical properties and microstructure of the aluminum matrix nanocomposites were investigated. Results show that the mechanical properties of the nanocomposites are improved by addition of TiO₂ coated GNPs, compared with those of nanocomposites with pure GNPs. The yield strength, ultimate tensile strength, and microhardness of the nanocomposites reinforced by TiO₂ coated GNPs are increased by 38.9%, 34.4%, and 20.1%, respectively, compared with those of the matrix. The improvement of the mechanical properties is attributed to the coating layer, which optimizes the interface bonding between the reinforcement and the matrix, thereby improving the efficiency of load transfer.

Abstract:A series of (Zr_0.6336Cu_0.1452Ni_0.1012Al_0.12)_100-xTm_x (x=0~5, at%) bulk metallic glass (BMG) alloys were fabricated by copper mold suction casting, and the effect of Tm on the mechanical and corrosion properties were investigated. The results show that when Tm content increases to 3at%, the glass forming ability (GFA) and compressive plasticity are significantly improved, whereas GFA is decreased by adding excessive Tm. The maximum supercooled liquid region width (ΔT_x) of the alloy with x=3 is 100 K, the compressive fracture strength is 1669 MPa, and the plastic strain is 21.01%, which are much higher than those of the Zr_0.6336Cu_0.1452Ni_0.1012Al_0.12 BMG (67 K, 1439 MPa, and 5.90%). However, the electrochemical test results show that the alloy with x=3 does not have excellent corrosion resistance in 3.5wt% NaCl solution, and the change trend of corrosion resistance and mechanical properties with Tm content is different from the expectation. The possible reason is that the excessive addition of rare-earth element Tm easily causes more oxides, which leads to the severe pitting corrosion. Further addition of Tm can improve the integrity and pitting corrosion resistance of Zr-based BMG passivation film, but the mechanical properties are not ideal.

Abstract:Three kinds of Mo-B-Ni-Cr ball-milled mixture powders with different (Mo+B)/(Ni+Cr) mass ratios (1:1, 2:1, and 3:1) were deposited by the high velocity oxygen-fuel (HVOF) spraying process to in situ synthesize MoB/NiCr coatings. The microstructure and phase composition of MoB/NiCr coatings were analyzed by scanning electron microscope (SEM) and X-ray diffraction (XRD). The effects of different (Mo+B)/(Ni+Cr) mass ratios on the microstructure, microhardness, bonding strength, and corrosion resistance of MoB/NiCr coatings were discussed. The results show that MoB/NiCr coatings with (Mo+B)/(Ni+Cr) mass ratio of 1:1 have the lowest porosity and the largest thickness. Mo₂NiB₂ ternary boride was in situ synthesized in all three kinds of MoB/NiCr coatings. The content of Mo₂NiB₂ ternary boride is increased with increasing the (Mo+B)/(Ni+Cr) mass ratio. The microhardness of MoB/NiCr coatings is increased with increasing the (Mo+B)/(Ni+Cr) mass ratio, while the bonding strength is decreased. After immersion test in molten zinc for 360 h, no zinc or its intermetallic compound can be observed in the surface region of MoB/NiCr coatings according to energy disperse spectrometer (EDS) and XRD analyses. The porosity of the coatings is increased with increasing the (Mo+B)/(Ni+Cr) mass ratio, while the thickness is decreased. Compared with other coatings, the MoB/NiCr coating with (Mo+B)/(Ni+Cr) mass ratio of 1:1 has better corrosion resistance in molten zinc.

Abstract:Using TiO₂, V₂O₅, and Al as raw materials and Mg and Ca as reducing agents, a novel method for preparing Ti6Al4V alloy powder through multistage deep reduction process was introduced. This new process has higher productivity and less pollution than traditional metallurgical process does. The results of self-propagating primary reduction experiments show that Mg is a more suitable reducing agent than Ca in the specific stage, and the porous Ti-Al-V-O precursor material with 6.74wt%~16.4wt% oxygen can be obtained when the amount of reducing agent Mg is appropriate. The Ti6Al4V powder with 0.24wt% oxygen can be obtained after the further calciothermic deep reduction (holding at 1173 K for 3.5 h).

Abstract:GH3039 superalloy was used as the third body metal to weld γ-TiAl with carbon steel, and the interface structure of the TiAl/GH3039 friction welding joint was analyzed by scanning electron microscope (SEM) and transmission electron microscope (TEM). The results show that the maximum tensile strength of the weld joint is more than 400 MPa after friction welding of γ-TiAl and GH3039 alloys. The plastic deformation of thermo-mechanically affected zone (TMAZ) on GH3039 side is larger than that on TiAl side, and dynamic recrystallization occurs on both sides. The Ni and Ti contents in the phase layer close to GH3039 and TiAl alloys hardly change, respectively. In the welding zone near GH3039 side, the distribution of Ni-rich and Cr-rich grains are complementary. Ti and Al are easily soluble in the Ni-rich crystal grains, and Mn is easily soluble in the Cr-rich crystal grains. A large number of Cr-rich grains formed in the bonding zone have body-centered cubic structure of α-Cr. The interface microstructure of the friction welding zone between γ-TiAl and GH3039 alloys is γ-TiAl+α₂-Ti₃Al/α₂+τ₃/τ₃-Al_1+x-yTi_1+yNi_1-x/τ₃+α-Cr/(Ni, Cr)_ss/GH3039.

Abstract:The modified Bridgman directional solidification technique was used to prepare the Ni-Si eutectic composites at solidification rate of 25 μm/s. However, the formation of metastable phase Ni₃₁Si₁₂ was inevitably during solidification process. Annealing treatment was conducted to reduce the number of metastable phases. Electrochemical impedance spectroscopy and potentiodynamic polarization techniques were used to analyze the corrosion resistance of Ni-Si eutectic composites in the 7wt% H₂SO₄ solution at 25 °C. The equivalent circuit was analyzed. Results show that the passivation performance and corrosion resistance behavior of Ni-Si eutectic composites are improved after annealing at 1050 °C for 4 h, which is mainly attributed to improvement of content and distribution of metastable phase Ni₃₁Si₁₂. The less the content of metastable phase, the stronger the corrosion resistance.

Abstract:CoCrFeNi high entropy alloys (HEAs) were prepared by electro-deoxidization of metal oxides in CaCl₂ molten salt at 1173 K. The phase transformation from the metal oxides to HEA under different electrolysis durations was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The results show that the formation process of CoCrFeNi HEA includes two stages: the rapid deoxidization stage and deep deoxidization stage. In the rapid deoxidization stage, 93.93wt% oxygen in sintered oxide pellet is removed within 1 h and the current efficiency reaches 89.95%. After electrolysis of 15 h, the oxygen content of the product is 0.26wt% and the current efficiency is 17.93%. The formation process of CoCrFeNi HEA provides guidance for establishing the electrochemical route with low cost and high efficiency.

Abstract:The microstructures and mechanical properties of the Al-Zn-Mg-Cu-Zr alloy processed by high pressure torsion (HPT) at 400 °C were analyzed by transmission electron microscopy (TEM), electron back-scattered diffraction (EBSD), and Instron testing machine. The results show that the grain boundaries and the secondary phases in the grains of deformed specimens are significantly broken and refined, and the width of precipitation-free zones at the grain boundaries narrows, which greatly improves the strength and plasticity of the deformed specimens. The grain orientation of the initial specimen is randomly distributed. When the strain is small, the grain size, grain orientation, and the local orientation difference of the specimen all present heterogeneous lamellar distribution. The deformed specimens of 0.5 turn exhibit the optimal mechanical properties due to the back stress strengthening effect caused by the heterogeneous lamellar structure during deformation.

Abstract:A simplified computational model for obtaining large piezomagnetic effect of magnetostrictive-electromagnetic hybrid vibration energy harvester was presented. During the model establishment, the influence of compressive stress ?σ and magnetic field ΔH on the piezomagnetic effect of Tb_0.3Dy_0.7Fe₂ alloy was studied, and their separate influence on magnetic flux density ?B of magnetostrictive material was investigated. Then, two methods, pre-loads-based method and impact stress-based method, were used to discuss the optimal criterion of hybrid piezomagnetic effect for the fabrication of magnetostrictive-electromagnetic generator. Finally, the modeling accuracy for obtaining large piezomagnetic effect was testified, and the experiment and theoretical results were in good agreement. Results show that the modeling can efficiently and accurately obtain the piezomagnetic effect for hybrid magnetostrictive material-based harvester under different application environments, which is of significance for design and fabrication of magnetostrictive-electromagnetic hybrid vibration energy harvester for obtaining large piezomagnetic effect.

Abstract:Effects of Y and Zr doping on the phase constituent, magnetic properties, and temperature stability for CeFeB alloy were investigated. The results show that CeYFeB alloy consists of the 2:14:1 main phase and a small amount of α-Fe phase. Magnetic properties including coercivity, remanence, and magnetic product energy improve considerably after Y doping. Meanwhile, the temperature stability is enhanced significantly. Due to the excellent intrinsic magnetic properties and higher temperature stability of Y₂Fe₁₄B phase, the remanence and coercivity temperature coefficients are -0.32%/K and -0.41%/K, increasing by 38.5% and 40.6%, respectively, compared to those of the pure CeFeB alloy. After the Y and Zr co-doping, the coercivity, remanence, and magnetic product energy improve greatly, increasing by 30.9%, 58.1%, and 204.8%, respectively, compared to those of pure CeFeB alloy, because of the joint effects of enhanced magnet crystalline anisotropic field and refined grain size.

Abstract:Electrodes consisting of LiNi_1/3Co_1/3Mn_1/3O₂, aluminum foil, conductive additives, and polyvinylidene fluoride were coated with a thin graphene oxide layer via a simple screen-printing method. The cycle performance and rate capability were tested at a cut-off voltage of 4.3 V. Results show that the capacity deceases whereas the polarization increases during the galvanostatic charge-discharge tests for primary electrodes. For the graphene-oxide-modified electrodes, the capacity decrement reduces and polarization increment rate evidently slows down. As a result, the cycle stability and rate capability are improved because the graphene oxide coating suppresses the side reactions between the LiNi_1/3Co_1/3Mn_1/3O₂ electrodes and electrolyte. The research provides an ecofriendly and highly effective strategy to improve the performance of LiNi_1/3Co_1/3Mn_1/3O₂ electrodes.

Abstract:The thermal parameter boundary conditions of the unstable deformation microstructure and dynamic recrystallized microstructure of BT25 titanium alloy were determined by the instability maps and power dissipation maps, respectively. The results were used in the Deform-3D finite element (FE) software to effectively combine the processing map technique with FE technique. The FE codes after secondary development were used to simulate and predict the unstable deformation zones and dynamic recrystallization (DRX) behavior of BT25 titanium alloy at the deformation temperature of 950~1100 °C and the strain rate of 0.001~1 s^-1. The reliability of simulation results was verified by metallographic microstructure. Results show that the flow stress is decreased with increasing the deformation temperature or decreasing the strain rate. The unstable deformed microstructure is concentrated in the region of low temperature and high strain rate. Both high temperature and low strain rate are beneficial to DRX behavior. The results of metallographic microstructure are in good agreement with those of simulation, indicating that the method of combining processing map technique and FE technique is reliable and feasible for predicting the unstable deformed microstructure and DRX behavior in the metal forging process.

Abstract:The molybdenum alloy has received more and more attention in various industrial fields, but its extensive applications are restricted due to the degradation of its creep resistance, strength, and oxidation resistance at high temperature, and the lack of effective mass production methods. This research analyzes the brittleness source of pure molybdenum, and reveals that the improvement of extrinsic brittleness and innovation of preparation process are the key directions of research and development of molybdenum alloys. The methods applied for strengthening and toughening of molybdenum alloys are reviewed, and the research and application status of typical molybdenum alloys are listed. In addition, in consideration of the existing problems, the research direction of high temperature molybdenum alloys is summarized.

Abstract:According to the micromechanics of composites, the effective elastic respond of Ni-base superalloy was predicted and the parameters of effective elastic propeties of GH4169 as well as its constituent materials i.e. effective elastic modulus E ?, effective bulk modulus K ?, effective shear modulus G ? and Possion’s ratio ν ?, were also theoretically calculated on the bases of macroscopic stress-strain relationship. The results, compared with the theoretically calculation and the experimental measurement in article, are shown that the error of effective elastic property parameters of GH4169 is 7.16%、10.69%、6.58%、0.67%, respectively ; the error 1.42%、0.40%、2.00%、1.66% for γ" phase, which proves the accuracy of the theory. Furthermore, the mesomechanical elastic respond of Ni-base superalloy was predictd in theory and the diffraction elastic constants of γ-(Ni-Cr-Fe) phase of GH4169 alloy, E_220=233.89GPa, ν_220=0.284 were also calculated theoretically, based on mesomechanical stress-strain relationship of Ni-base superalloy under uniaxial loading. Simultaneously, the diffraction elastic constants of the (220) crystal plane of γ-(Ni-Cr-Fe) phase were experimentally measured with the combination of four-point bending to calibrate the load stress and X-ray diffraction for diffraction strain measurement. Contrasted between the theoretical and experimental, the results are demonstrated that the experimental E_220=248.00GPa, ν_220=0.276 and that difference between the theoretical calculation is 5.69%, 2.90% respectively, which proves the accuracy of the theoretical model and also provides a theoretical basis for the study of residual stress measurement by diffraction method as well.

Abstract:A novel process named Expansion non-equal channel angular extrusion (Exp-NECAE) is proposed, which integrates various deformations including upsetting, shearing and extrusion in a single pass. Based on the theoretical analysis, severe plastic deformation behavior of commercially pure aluminum under multi-deformation coupling effects was investigated by numerical simulation and experimental verification, and the evolution of microstructure and mechanical properties of the processed materials was discussed. The results show that Exp-NECAE process has the advantage of high efficiency as a compound deformation method, the billet was extruded continuously, stably and compatibly, and the deformation process can be classified into three different stages: corner area deformation, transition area deformation and extruded area deformation, respectively. During the process, the processed material was in an ideal three-dimensional compressive stress state with homogeneous deformation distribution. The accumulative strrain was as high as 2.56 after a single pass of extrusion, which was close to the theoretical calculation. After one pass of Exp-NECAE, under the simple shear strain induced by the coupling effects of upsetting, shear and extrusion, the grain size of commercial pure aluminum was significantly refined, forming a mixed microstructure dominated by ultrafine equiaxed grains with an average grain size of around 2.73 μm. Moreover, the mechanical properties of the processed material were significantly improved. The average microhardness was 55.8 HV, and the tensile strength and the elongation can reach up to 161.2 MPa and 13.9%, respectively. A large number of small and deep dimples were observed in the fracture morphology, and the distribution was relatively uniform, showing a good ductile fracture characteristics.

Abstract:Four types of samples were obtained by anodizing 7B04 aluminum alloy with sulfuric acid or chromic acid and then spraying primer or primer and topcoat. Then a standard filiform corrosion test was carried out and the corrosion behavior and mechanism of 7B04 aluminum alloy/coating systems were investigated by scanning Kelvin probe and Fourier transform infrared spectroscopy (FT-IR). Optical microscope observations reveal that the number of filaments on the four types of samples is small, and the length is no more than 3 mm, indicating that the four types of specimens all have good corrosion resistance. The results of SKP tests show that the variation of Volta potential of the scribe mark and adjacent area with the test time is similar among the four kinds of samples. The potential difference between the scribe mark and the adjacent coating-metal interface causes the occurrence of filiform corrosion, and the corrosion mechanism is anodic undermining. The Volta potential of a single filament decreases towards the head and increased towards the tail, and the potential difference between the head and the tail promotes the propagation of the filament. The results of FT-IR show that the main components of corrosion products at the scribe mark and under the filament are Al(OH)3, Al2O3, AlCl3，and its partially hydrolyzed products. The main chemical reactions in the filiform corrosion are similar to the pitting corrosion of 7B04 aluminum alloy under the erosion of chloride ion. Comparative analysis shows that the influence of two anodic oxidation modes on filiform corrosion is less different

Abstract:The quasi-peritectic reaction, which has dual characteristics of eutectic and peritectic reaction, exists in many ternary alloy systems. However, its solidification characteristics and its solidification mechanism is still unclear so far. To address this question, the Nb10Ti61Co29 alloy near the quasi-peritectic point was selected as the research object in this paper, and a series of directional solidification experiments with different growth rates (ν=1, 3, 5, 15, 30, 70 μm/s) were carried out using Bridgman directional solidification technique. Then the solidification structure at each growth rate was analyzed by XRD, SEM and EDS, and the microstructure evolution law of these directionally solidified samples was clarified. The results show that, the solidification structure of this alloy at different growth rates includes initial transition zone, steady-state growth zone and quenching zone. As the growth rate increases, the profile of the initial growth interface in the initial transition zone becomes more and more clear. With these changes, the relationship between the steady-state growth region and the initial transition region becomes smaller. Moreover, the quenching interfaces go through the transition from flat-bound to cell-oriented to dendrite in turn with the increase of the growth rate. In especial, the quenching interface is flat when the growth rate is 1 μm/s, whereas the quenching interface is roughly cellular when the growth rates are 3 and/or 5 μm/s. Lastly, the following four solidification reactions will occur successively in the process of equilibrium solidification, which was calculated by CALPHAD method, (a) L→α-Nb; (b) binary eutectic reaction L→α-Nb + TiCo;α-Nb TiCo; (c) ternary quasiperitecticcoated reaction L+TiCo→α-Nb +Ti2Co and (d) binary eutectic reaction L→α-Nb + Ti2Co.

Abstract:Research the hot deformation behavior and microstructure evolution of Ti80 alloy through hot compression tests, investigate the stress-strain curve and work hardening law of the alloy, and establish the hot processing map of the alloy. Then, Ti80 alloy sheets under different hot rolling processes were prepared, and the microstructure changes and their effects on mechanical properties were studied. Explore the process conditions for Ti80 alloy with optimal mechanical properties. The result shows: The peak stress and work hardening rate of Ti80 alloy decrease with the increase of deformation temperature and decrease of deformation rate. there exist strain rate and deformation temperature sensitivity in this alloy. According to the calculation and analysis of the hot processing map, the temperature range of 800℃~920℃, 920℃～1050℃, and strain rate of 0.01s-1～0.1s-1 is the best stable deformation zone.As the deformation temperature increases, its microstructure undergoes a change from equiaxed grain structure, duplex structure to fully lamellar structure. At the same time, as the strain rate increases, there is a change in the morphology of the β transition matrix. The mechanical properties of Ti80 alloy under different hot rolling conditions are compared and analyzed. When the initial rolling temperature is 1060℃ and the final rolling temperature is 950℃, it shows a mixed microstructure of basketweave microstructure + block α phase, which has the best tensile strength and plasticity performance, tensile strength is 881Mpa, and elongation is 11.27%, showing ductile fracture.

Abstract:Two electrode materials, homogeneous NiO/Ni(OH)₂ with micropits and NiO/Ni(OH)₂(B) with microspheres, were prepared on the surface of copper sheet by electroless plating and subsequent electrochemical anodic oxidation. The results of SEM, XRD and XPS showed that the two electrode materials were composed of Ni, NiO and Ni(OH)₂, and the doped of B in NiO/Ni(OH)₂(B) was up to 14.6wt%. The cyclic voltammetry measurements and galvanostatic charge-discharge tests show that both electrode materials possess high electrochemical activity and reversibility. At the charge/discharge current density of 1 A/g, the specific capacitance of 1380 and 1930F/g of two kinds of NiO/Ni(OH)₂ and NiO/Ni(OH)₂(B) electrode materials after 10000 charge/discharge cycles are respectively obtained, showing high specific capacitance and good electrochemical stability. The electrochemical impedance spectroscopy shows that the electrochemical reaction resistance of NiO/Ni(OH)₂(B) electrode material is about 2 orders of magnitude lower than that of NiO/Ni(OH)₂. The Ragone curve reveals that the two electrode materials have higher power density and lower energy density. The doped of B in the NiO/Ni(OH)₂(B) electrode materials increases the surface oxide content and forms micron microsphere morphology, which results in the increase of electrode surface area and the improvements of the contact and wettability between the electrode and the electrolyte, and the decrease of the band gap energy on the surface of electrode. These are the main reasons for its excellent pseudo-capacitance performance.

Abstract:The microstructure and mechanical behavior of solution treated Ti-41Nb alloy were systematically investigated by optical microscope, tensile test and in situ synchrotron high-energy X-ray diffraction. After solution treated at 800℃ plus water quenching, Ti-41Nb alloy presents a typical dual-phase structure which is characterized by exiguous lath-shaped α" martensite distributed on the equiaxed β matrix. The stress induced martensitic transformation (SIMT), together with elastic deformation, takes place concurrently during loading. The stress-induced martensitic transformation from β to α″ takes place intensively in the strain range from 0.0% to 3.3% but slightly from 3.3% to 4.0%. In the subsequent unloading process, the solution treated Ti-41Nb alloy undergoes elastic recovery, accompanied by the reverse martensitic transformation from α″ to β. After unloading, a large amount of α″ martensite has not been transformed into β parent phase, which results in a residual strain of 2.9%.

Abstract:TC4 titanium lotus-like core sandwich structure was brazed using TiZrCuNi brazing filler metal. Effect of brazing parameters on brazing interface microstructure and mechanical properties of titanium lotus-like core sandwich structure was investigated. Results show that titanium sandwich structure with excellent brazed quality is attained at the brazing temperature of 920 ℃ with the brazing time of 90 min. The microstructure of the brazing interface consists of acicular α structure and Ti-Cu intermetallic compounds, and the average flat compressive strength of the sandwich structure is 15.14mpa. When the brazing time is short (15min), the diffusion reaction time between Cu and Ni in the liquid solder and the base metal is short, and the diffusion reaction of Cu and Ni into the base metal is not sufficient. The enrichment of Cu and Ni in the brazing interface leads to the content of Cu and Ni exceeding the eutectic composition, which makes eutectic reaction occurred during the solidification process of liquid solder joint after brazing, and thus massive intermetallic compounds are formed. The brazing interface is mainly composed of solidified brazing filler metal containing massive intermetallic compounds and acicular α structure. With the increase of brazing time, the diffusion reaction time of Cu and Ni elements in liquid solder and base metal increases, and the diffusion reaction depth of Cu and Ni elements into base metal increases significantly. As a result, the content of Cu and Ni in the liquid solder decreases significantly, and the element content is less than the eutectic composition point. Cu and Ni are all dissolved in β phase during the solidification process of the liquid brazing seam. When the β phase changes to α phase, the acicular α phase is formed by eutectoid reaction, and intermetallic compound is formed at the interface of acicular α structure. When the brazing time increases from 15min to 90min, the flat compressive strength of TC4 titanium sandwich structure increases gradually due to the decrease of intermetallic compounds in the brazing interface.

Abstract:GH3536 alloy is the main material of aero engine fuel nozzle. Compared with the traditional processing technology, laser solid forming technology（LSF）has the advantages of near net forming, which is more suitable for the production of complex structural parts and reduces the cost. The scanning path plays an important role in LSF. In this paper, metallographic, XRD, SEM and tensile testing methods were used to explore the influence of 45° cross grating and zig-zag cross grating scanning paths on GH3536 alloy fabricated by LSF. The results show that the two scanning paths have little effect on the microstructure of GH3536 alloy fabricated by LSF. The substrate of two scanning paths are γ phase. There are M23C6 carbides in the grain boundary, and there are both M23C6 carbides and M6C carbides in the grain. The heat accumulation of zig-zag cross grating is slightly higher than that of 45 ° cross grating, resulting in larger porosity and higher forming height. The tensile properties of the two scanning paths are similar. The fracture mode is ductile fracture, and the crack occurs at the carbide, mainly transgranular fracture.

Abstract:XRD, FEG-SEM and EDS were used to study the oxidation resistance of alloys with different Ta element contents at 800℃. The results show that the relationship between oxidation weight gain and oxidation time of Ta-containing alloys conforms to parabolic kinetics law, and the oxide layer is Al₂O₃+NiCr₂O₄+Ta₂O₅+(Ti/Cr)TaO₄ composite oxide structure, and with the increase of Ta content, the thickness of the oxide layer decreases, and the oxidation depth becomes thinner, and the oxide layer becomes smoother and denser. Experiments have found that there is a Ta-rich oxide (Ta₂O₅, (Ti/Cr)TaO₄) between the outer layer and the inner oxide layer, which can easily combine with Cr₂O₃ to form CrTaO₄, which reduces the volatilization loss of Cr₂O₃ oxide at high temperatures and improves the oxidation resistance of the alloy. Experiments show that Ta-rich Ta₂O₅ and (Ti/Cr)TaO₄ can hinder the out-diffusion rate of metal ions. The addition of Ta changes the ion diffusion rate of the oxide layer and improves the oxidation resistance of the alloy.

Abstract:Ni-F co-doped Nano LiNi0.03Mn1.97O3.95F0.05 (LNMOF) cathode material was synthesized by a molten-salt combustion method. The results show that Ni-F co-doped markedly elevates the rate performance, cycling stability and specific capacity of the LNMOF. At 5, 10, 15, 20 C and 25 ℃, LNMOF exhibits the initial discharge capacity of 101.4, 92.5, 89.4 and 66.8 mAh?g-1 respectively. After 1000 cycles, the LNMOF deliver capacity retention rate of 77.9, 70.8, 70.9 and 72.9% respectively. Cyclic voltammetry and electrochemical impedance spectroscopy show that LNMOF cathode material exhibits lower apparent activation energy 24.72 KJ?mol-1 and greater diffusion coefficient of lithium ion 1.174×10-8 cm2?s-1, when compared to the LiMn2O4 sample. The electrode of before and after 1000 cycles were investigated via XRD, it was demonstrated that the crystal structure of the LNMOF sample has hardly changed. Moderate Ni-F co-doping effectively inhibits Jahn-Teller distortion, stabilizes crystal structure and improves the specific capacity and enhances the cycle performance of LiMn2O4 cathode materials at the same time.

Abstract:In view of the waste lithium ion batteries increasing, the technologies for recycling and regeneration of spent LiCoO2 batteries have been explored. In this paper, LiNi0.8Co0.1Mn0.1O2 cathode material was re-synthesized from discard LiCoO2 batteries through pre-treatment, acid leaching and co-precipitation. he concentration of metal ion in leachate were analyzed by ICP-OES, the morphology and structure of cathode materials were characterized by the SEM and XRD, the electrochemical properties of coin batteries were performed by the electrochemical tests. The results showed that the regenerated material from acid leaching lixivium exhibits the desired morphology and well layer structure. Under the condition of 2.8~4.3V, the initial discharge capacity of regenerated material is 210.8 mAh/g at 0.2C. After 50 cycles, the capacity retention of re-synthesized cathode material is 87%, showing good cycle performance, which will support the recycling process for spent Li-ion batteries

Abstract:In recent years, with the development of industrial production, the repair and bonding of wide gaps has always been a key technology. In this study, a gap (width of 20 mm) was bonded by wide gap brazing technology. The K417G superalloy was used as the base metal, and a mixture of low-melting powder (LMP) and high-melting powder (HMP) was used as the filler metal. In this research, K417G superalloy was brazed by different contents of LMP + HMP mixed powder. The microstructure evolution and mechanical properties of joint was analyzed. With increasing the ratio of HMP in the filler metal, the borides in the joint was decreased and the uniformity of composition and microstructure of joint was improved. When the ratio of HMP in the filler metal increased to 95 wt.%, B can be uniformly diffused into the HMP and brittle borides at the interface were significantly reduced. The tensile strength of the joint at room temperature and 600 °C was 971 MPa and 934 MPa, reaching the strength of base metal. In addition, the fine particles of M23(C, B)6 carbon-boride are coherently precipitated in-situ in the joint and uniformly dispersed, facilitating excellent repair.

Abstract:The bimetal plate is widely used because of its good performance. But the development of single point incremental forming is hindered by the processing defects that affect the accuracy and forming performance of parts such as bottom bulging and side wall bulging. The variations of forming accuracy of the single point incremental forming have been analyzed by using a combination of experiment method and finite element method. The results show that the bottom bulge height and the side wall bulging are most affected by the forming angle and forming depth respectively. These results indicate that the height of the bottom bulge is reduced by 29% and the side wall bulging is increased by 18.5% when the forming angle increases from 30°to 60°. The height of the bottom bulge is decreased by 13% and the side wall bulging is decreased by 16% when the tool head diameter is increased from 10mm to 20mm. The height of the bottom bulge is decreased by 24% and the side wall bulging is increased by 18.3% when the step down size from 0.2mm to 0.5mm. Finally, reasonable process parameters were optimized, so that the bottom bulge height decreased by 49%, and the side wall bulge decreased by 41%.

Abstract:By means of optical microscope (OM), field emission scanning electron microscope (FE-SEM) and series properties tests, the effects of the mixed-grain micromicrostructure on mechanical property of nickel - based superalloy GH4720Li was studied in this paper. The results were as follows, the tensile strength and yield strength at 650℃ for specimens with portional local coarse grain are slightly lower than that with uniform fine grain under the tensile tests at high temperature. The tensile strength drops rapidly with the increasing of volume percentage of coarse grain. Furthmore, the deformation mechanism of superalloys at high temperature is not the same under different stress-rupture test conditions.Under the temperature and stress condition of 730℃/530MPa, the stress-rupture life increases with the increasing of volume percentage of coarse grain for the reason that grain boundary sliding mechanism plays an important role. While the major deformation mechanisms is found to be dislocation gliding under 680℃/830MPa. Therefore, the stress-rupture life decreases with the increasing of volume percentage of coarse grain. Under this condition, the specimens with local coarse grain and fine grain have the best stress-rupture property. Grain boundary sliding also have certain effect under the condition, which results in not obviously reduction of the stress-rupture life for specimens mainly with coarse grain.

Abstract:The effect of different Ce content on the microstructure and mechanical properties of Cr30Mo2 superferrite stainless steel was studied. The results show that the inclusion types in Cr30Mo2 superferrite stainless steel are mainly Cr oxides and Al-Si composite oxides with irregular shapes, which are converted into Ce2O3 after Ce addition and spherical composite inclusions rich in Al and Si in the core and Al and Ce in the outer layer, with small size, round shape and significantly reduced inclusion content. Ce2O3 can be used as heterogeneous nucleation core, which can increase casting nucleation rate and reduce grain size. However, excessive Ce content results in abnormal increase of grain size. Trace Ce can significantly improve the plasticity of Cr30Mo2 stainless steel at room temperature. Adding 0.07%Ce can increase the elongation after fracture from 1.5% to about 20%.

Abstract:The practical application of Zr-based amorphous alloys is hindered by the brittleness of the material and the harsh preparation conditions, which are closely related to its lack of slip shear band and limited amorphous forming ability. Therefore, the rare earth ytterbium (Yb) doped Zr-based amorphous alloy thin film was successfully prepared by magnetron co-sputtering, using scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X Test methods, X-ray diffraction (XRD) and contact angle tester have studied the relationship between the amorphous forming ability and film properties of (Zr₄₈Cu₄₄Al₈)_1-xYb_x (x?at%) alloy and the rare earth doping concentration. The results show that the alloy system has the strongest amorphous forming ability when the doped Yb atom concentration is 9.37 at%. With the increase of Yb sputtering power, the pre peak at low angle gradually disappears, and the film layer evolves from single-phase Zr based amorphous to dual-phase amorphous, especially when the power is greater than 50 W, a new amorphous diffraction peak appears in XRD, and the diffraction peak intensity increases with the increase of power. Therefore, the best doping power for obtaining a single-phase Zr-based amorphous film layer is 10 W, and the rare earth elements in the film layer are uniformly distributed. At the same time, the surface roughness of the amorphous film appears to be an extreme point with the increase of sputtering power of Yb target, and the corresponding contact angle of the film is 104.9 ° at 30 W, showing hydrophobic property. Therefore, the rare earth Yb doping has a significant effect on the Zr-based amorphous forming ability and film properties. Keywords: amorphous alloy; rare earth alloying; ytterbium; magnetron sputtering ; composition design

Abstract:In order to further evaluate the scientificity and availability of materials selection scheme of the advanced 700℃ ultra-supercritical (700 ℃ A-USC) thermal power units, regular sampling and testing were conducted on the candidate tubes operating on the 700℃ A-USC test bed of Huaneng Nanjing Power Plant. Three groups of Inconel 740H superheater tubes with different operation time (0 h, 10,000 h, 24,000 h) were sectioned and machined, and then their mechanical properties and microstructure characteristics were evaluated by means of OM, SEM, TEM. Results show that the R_p0.2 and R_m of Inconel 740H at room temperature (RT) and 700℃ decreased slowly with the extension of operation time. The impact absorbing energy at room and high temperature both decreased significantly from original aging state to operation for 10,000 h, but when the operation time further prolonged to 24,000 h, only slight decrease was observed. The microstructure evolution of Inconel 740H was mainly manifested in the increase of grain boundary carbide M23C6 and the coarsening of γ′ particles. In general, Inconel 740H boiler tubes exhibited good mechanical properties and microstructure stability during operation.

Abstract:In order to produce high-quality SAC305 alloy spherical powder, we studyed the effects of operating parameters: rotating speed, melt feed rate, shape and size of atomizer, and oxygen content in the atomizer chamber on the performance to produce Sn-3.0Ag-0.5Cu powder by rotary centrifugal atomization. It was evidenced from the experimental results that the median size of the atomized powders became smaller with increasing rotating speed（6000-60000rpm）, decreasing melt feed rate(30-60kg/h the ), and use of larger atomizer（30-50mm）, the experiment value of n is 1.65，the CFD value of n is 1.65. A cup shaped atomizer was able to give approx. 8% finer powder compared to that from a flat-disk shaped one. SEM micrographs revealed that the oxygen content of the atomization chamber decreased, the powder sphericity factor approached 1. When the oxygen content in the atomization chamber was less than 400 ppm, the oxygen content on the powder surface was less than 100 ppm. The surface quality is the best when the superheat of the atomization chamber and the melt is 230℃, the atomization parameters control the particle size and sphericity of the powder. SAC305 powder particle size and sphericity are mainly controlled by the process, and the powder surface quality is related to the cooling efficiency and collection technology.

Abstract:In the present experiments, the casting samples of a third generation single crystal superalloy were solution heat treated in different atmospheres, in order to investigate the microstructure near the sample surface and to develop a suitable measure avoiding the Cr-depletion layer. Under high vacuum atmosphere, a depletion layer of alloying elements such as Cr, Co and Re was observed beneath the sample surface, with about 70 μm in depth. When the furnace chamber was filled with argon gas to protect the sample, unexpectedly, the oxidation of the sample surface occurred and the depletion incipient melting zone in a depth of about 1 mm was detected. This unusual phenomena may be attributed to the filling of the protective gas which caused the strong convection in the furnace chamber under very high temperature, in spite of the high purity of the used argon gas. When the sample was enclosed in a ceramic tube during heat treatment, the sample was located in a narrow space and isolated from the strong convection in the large furnace chamber. In this case, the reaction of casting sample with the furnace atmosphere was effectively suppressed during heat treatment process. Moreover, the evaporation of the alloying elements became quickly saturated within the narrow closed space. As a result, the serious depletion of the alloying elements from the casting surface was successfully avoided.

Abstract:In this paper, CoCrCuFeNi high-entropy alloy was successfully fabricated by spark plasma sintering (SPS) at 900 oC, 1000 oC, 1100 oC and 1150 oC. The tensile at room temperature results shows that the tensile strength of the CoCrCuFeNi alloy firstly decreases and then increase with the increase of sintering temperature. However, the uniform elongation firstly significantly increases and then decreases. When the sintering was carried out at 1100 oC, the yield strength and unltimate tensile strength of CoCrCuFeNi alloy reaches 379.3 MPa and 655.6 MPa, respectively, and the elongation after fracture is 21.9%. When sintering temperature above 1100 oC, the element segregation obviously appears in the material because of the local melting. Besides, the tensile fracture is brittle feature along the surface of the spherical powder at 900℃. While the fracture is a ductile fracture as the sintering temperature increases. Because of the diffusion of carbon atom during high temperature sintering, TEM results show that the carbon reacts with the matrix to form second phase carbide particles inside the matrix.

Abstract:In this paper, CdGa2O4 nanosheets were prepared by microwave-calcination method. CdGa2O4 nanosheets were characterized by X-ray diffraction (XRD)、scanning electron microscopy (SEM)、Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) et al. The effect of pH on the gas-sensing performance of CdGa2O4 nanosheets was investigated. The results showed that the sensitivity of CdGa2O4 which prepared by annealing at 700oC for 5h after precipitation at pH of 10 to 100 ppm formaldehyde was 316 at 110oC. The sensitivity of the gas sensor based on CdGa2O4 nanosheets to 0.01 ppb formaldehyde was 2.

Abstract:AlFeCoNiBx high entropy alloy was prepared by vacuum arc melting, and its microstructure and high temperature oxidation behavior were studied. The results show that the increase of B content leads to the transformation of the alloy from "pure B2 phase" to "B2 phase +(FCC1+FCC2)eutectic". After oxidation of AlFeCoNiBx at 900 ℃, With the increase of B content, the thickness of outer CoFe2O4 oxide increases rapidly, while that of inner layer Al2O3 remains unchanged. However, when the content of B exceeds 0.15at%, the continuity of oxide film becomes worse. When the content of B is 0.15at%, the oxidation weight gain is the smallest, the oxide film is well bonded with the alloy substrate, and the oxidation resistance is the best.

Abstract:The service performance of Zr alloy cladding can be enhanced by synthesizing a protective coating material on its surface, and also the zirconium-water reaction under steam higher than 1200℃ is delayed, so the accident tolerance of the current nuclear fuel assembly in the event of reactor loss of water is improved. Therefore, the coating technology is also listed as a short-term plan for the design and research of accident-tolerant nuclear reactors. In this study, a plasma enhanced physical vapor deposition technology was employed to prepare Cr coating on the surface of Zr-4 alloy, and ion bombardment and implantation was carried out specifically for the interface between coating and substrate. The properties of the coating system and its influence on the zirconium alloy matrix were evaluated. Compared with the uncoated Zr-4 substrate sample, the diffusion of oxygen into the Zr-4 substrate was obviously hindered and the formation of harmful hydrides was effectively inhibited in high temperature steam accelerated corrosion test by Cr coating. The Cr coated sample did not fall off, and the substrate was not be oxidized in the high temperature thermal shock test greater than 1000℃, but the uncoated substrate was totally oxidized. The tensile and internal pressure blasting tests also showed that the Cr coating exhibited good adhesion to the Zr-4 substrate, with little effect on mechanical properties of Zr-4 substrate. It can be considered that the Cr coating is one of the ideal accident-tolerant coating materials on Zr-4 cladding.

Abstract:_{:Rare metals are commonly used in the manufacturing process of magnesium alloys, and the Pidgeon process is usually used for magnesium production, the production of magnesium is in vacuum, which resulting in discontinuous, it is necessary to study the condensation behavior of magnesium vapor in vacuum, which can provide theoretical support for continuous production. The condensation behavior of magnesium vapor at different volatilization temperatures and temperature gradients is studied. The results show that the increase of volatilization temperature, the initial condensation temperature decreases, the condensation region span of magnesium vapor increases, and the particle size of condensation products decreases. The volatilization temperature increased from 1000 ℃ to 1200 ℃, the initial condensation temperature of magnesium vapor decreased from 400.1 ℃ to 344.7 ℃, the span of magnesium condensation area increased from 11.5 cm to 16 cm, and the particle size of magnesium vapor condensation decreased from 68.33 μm to 24.60 μm. The temperature gradient increases, the span of condensation region becomes shorter, and has little effect on particle size. The research results can be used to guide the continuous production process of magnesium and the design of condenser for continuous magnesium production.}

Abstract:Compared with traditional biomedical metal materials, such as titanium alloys, stainless steels, cobalt-base alloys, magnesium alloys not only possess biodegradable properties, but also its elastic modulus is close to human bone, so it is hard to induce the effect of ing", so it is known as "new generation of advanced biomaterials". However, the degradation rate of magnesium alloy in human body is too fast, resulting in mechanical instability and metabolic absorption of excessive degradation products in vivo, which limits its application in the field of surgical implant and intervention. Biodegradable or absorbable natural and synthetic polymers are a kind of biomedical materials with light weight, multi-function and good biological safety. If they are used as special protective coating on the surface of degradable magnesium alloys and deal well with the biological function and mechanical compatibility of surfaces between them, it will be important direction to develop advanced magnesium alloys materials and their applications. In this paper, the latest research progress of biodegradable natural and synthetic polymer coatings on magnesium based alloys is reviewed, and the development trend of its research and development and application in the future is put forward.

Abstract:Magnesium-based alloys were known as the new generation ‘revolutionary medical metal materials’, due to its better biological safety, excellent mechanical bearing effect and controllable degradation rate in vivo and in vitro. However, the corrosion resistance of magnesium alloy is very poor under the humid atmosphere. Particularly in a complicated human physiological environment, implant materials need to undergo the synergistic effects of dynamic alternating load and corrosive medium. Thus, it can cause the mechanical fixation and mechanical support roles of the Mg-based alloys decreased dramatically, resulting in the premature implantation failure. As a result, the coupling mechanism of applied load, frequency and corrosion factors affecting fatigue failure of medical magnesium alloys was investigated. In view of the quantitative relationships between corrosion fatigue life, fracture micro-zone characteristics and corrosion rate of biomedical Mg alloys in vivo and in vitro, the microscopic mechanism of corrosion fatigue failure under cyclic loading was described. Meantime, the initiation and propagation mechanism of fatigue micro-cracks were thoroughly analyzed; the improvement methods of corrosion fatigue properties of Mg alloys were comprehensively summarized; and the application prospect and development direction of biodegradable magnesium alloys for biomedical use were forecasted.

Abstract:The mineral resources of platinum group metals are predominately localized in South Africa and Russia, the resources of PGMs in China is quite scarce, but China is the world"s largest consumer of platinum group metals, mainly used in the field of catalyst manufacturing. Therefore, the efficient recovery of PGMs form secondary resources is a major strategy to solve the contradiction supply and demand of PGMs in China. In this review, the resource reserve, consumption and supply distribution and secondary resource recovery of PGMs were discussed in detail, and focuses on the recovery process of PGMs from spent automotive catalysts with cordierite-based honeycomb monolith morphology. Hydrometallurgical process mainly include direct dissolution of valuable components and supporter dissolved to enrichment PGMs, the pretreatment of spent automobile catalyst is the key factor to improve the leaching efficiency of PGMs, although some hydrometallurgical process have the benefits such as flexible production process, low cost, high PGMs recovery efficiency, and widely applied, but their disadvantages of hazardous waste must be carefully evaluated. Pyrometallurgical process include efficient chloride salt extraction of PGMs and metal capture enrichment PGMs, the collector include copper, lead, iron and matte, the technology has the advantages of simplified process, highly enrichment efficiency and easily scale production. The advantages and disadvantages of various process are summarized, based on the environmental pollution, high energy consumption and low recovery of PGMs, a new approach for recovery of platinum group metals in spent automotive catalysts by a cost-effective, low temperature, environment friendly and pollution-free capture technology via Bismuth was proposed , and a new direction for efficient enrichment of PGMs from spent automobile catalysts were provided.

Abstract:Tungsten-based materials with high melting point, high thermal conductivity, low vapor pressure and low tritium retention have become plasma oriented materials with broad application prospects. Due to its shortcomings in low temperature brittleness, recrystallization brittleness and irradiation damage, its application in engineering is limited, and it has become a research hotspot in the field of nuclear fusion materials. In this paper, the research status of tungsten-oriented plasma-oriented materials is reviewed, the damage caused by four kinds of particle irradiation and four kinds of commonly used methods to improve the properties of tungsten materials are described, and the problems that need to be solved are also discussed.

Abstract:S : Graphene and its derivatives were reviewed in detail, such as strengthening phase and the application scope and applicable difference between the different preparation methods of metal matrix composites are compared and analyzed between the traditional preparation methods of the classification of the characteristics and application direction, mainly puts forward the process step is flexible, controllable high new graphene preparation of the method of laser reinforced metal matrix composite material manufacturing technology.In-depth discussion of graphene and its derivatives as enhancement phase, brought in the metal matrix composite mechanics, tribology, electricity, the change of metal corrosion resistance performance, compared the graphene and derivatives as enhanced relative to aluminum, magnesium, nickel, copper, titanium metal matrix composites, such as performance improvement and improve the level and still exist in different metal matrix composites reinforced phase all sorts of agglomeration and dispersion problem and the interface bonding of metal substrate and the treatment scheme is put forward, finally put forward the preparation of graphene metal matrix composites in the future development direction and new preparation technology of the practical problems still exist.

Abstract:In the process of copper smelting, a large amount of copper slag is produced and gold and silver are discharged along with copper slag. In order to reasonably recover gold, silver and copper from copper slag, a vortex dilution method was proposed. The molten copper slag was used as raw material, the gold, silver and copper in copper slag were recovered through the vortex dilution process, and the diluted slag was further reduced to produce copper-containing molten iron, which could finally be prepared into wear-resistant cast iron or copper-containing antimicrobial stainless steel. The results showed that Fe3O4 in copper slag was reduced to FeO by FeS and then FeO combined with SiO2 to form Fe2SiO4. After vortex dilution, the recovery rates of gold, silver and copper reached 99.44%, 93.97% and 93.14%, respectively. The content of Fe3O4 and Cu in diluted slag were 1.53% and 0.61%, respectively. The copper-containing molten iron was obtained from the diluted copper slag by vortex reduction and then used to produce the wear-resistant cast iron, the element composition of which could meet the requirements of national standard of high chromium wear-resistant cast iron.

Abstract:As a new type of oxide system, high-entropy oxide breaks through the design concept of mutual doping of traditional alloys. It is obtained by solid solution of five or more oxides. It is widespreadly concerned due to its unique structure and potential application value. In this work, spinel-structured (FeCoCrMnCuZn)3O4 high-entropy oxidepowders were prepared by a facile solid-state reaction method and characterized by XRD, SEM, TEM and XPS. The results show that, with the increase of calcining temperature, Fe2O3, Cr2O3, MnO2, CuO and ZnO are successively dissolved into the spinel structure. Finally, (FeCoCrMnCuZn)3O4 oxide with a single spinel structure (face-centered cubic, Fd-3m) was obtained by calcining at 800 °C for 2 h. Fe, Co, Cr, Mn, Cu and Zn are uniformly distributed in the (FeCoCrMnCuZn)3O4 grains, which is a typical feature of high-entropy oxide. When the current density is 1 A/g, the mass specific capacitance of the synthesized (FeCoCrMnCuZn)3O4 high-entropy oxide powders is 152.9 F/g.