Abstract:In order to produce economical tungsten alloys with superior mechanical properties, 93W-4.6Ni-2.4Fe (wt%) tungsten heavy alloys were fabricated by ball milling and liquid phase sintering at a temperature range of 1450?1510 °C. The microstructure and the fracture modes of the specimens were examined. Results show that the specimens sintered at different temperatures display similar dual-phase microstructure and ductile fracture modes. With the increase in sintering temperature, the tungsten particle size also gradually grows. At the temperatures above 1480 °C, the relative density reaches above 99.0%. The optimal sintering temperature of the specimen with the best tensile strength (940 MPa) and elongation (32.6%) combination is determined to be 1480 °C. The excellent ductility of the specimen sintered at 1480 °C is associated with the network structure of γ phase, the uniform distribution of dimples and the synergistic effect of these two phases. The high strength of the specimen is attributed to the refined tungsten particle size and the spherical tungsten particles.

Abstract:A new refractory high entropy alloy WMoNbTaV containing Al₂O₃ was prepared by spark plasma sintering. The effects of sintering temperature on densification behavior, phase structure, microstructure and wear resistance of the alloy were studied. The results show that when sintered at 1800?1900 °C, the matrix of WMoNbTaV-Al₂O₃ has a single bcc phase structure, and the average grain size of Al₂O₃ is 1.15 μm. With the increase in sintering temperature, the grain size of the alloy increases, the density and microhardness also increase, and the hardness reaches 7967.4 MPa when the sintering temperature is 1900 °C. The alloy sintered at 1900 °C has excellent wear resistance, and the wear amount is only half of that of the alloy sintered at 1800 °C. The wear resistance of WMoNbTaV-Al₂O₃ high entropy alloy is much higher than that of pure W material. When the abrasive particle size is 37.5 μm, the wear mass loss of alloy sintered at 1900 °C is 0.9 mg, and the wear resistance of alloy is 83 times higher than that of pure W material.

Abstract:Dispersion strengthening plays an important role in improving the properties of alloys. The stability of carbide and oxide ceramics, as commonly used dispersion-reinforced particles, is important for alloys applied in nuclear reactors serving in harsh environments, so it is of great significance to study the radiation resistance of SiC, TiC, ZrC, Al₂O₃, Y₂O₃ and ZrO₂. The effects of different energies and different types of incident ions on different materials were simulated by SRIM program, and the irradiation damage of zirconia at different irradiation doses was analyzed. Results show that with the increase in incident ion energy, the distribution of the incident ions in the target material tends to be uniform and normal, and the stop position of the incident ions and the damage depth of the target material increase. The damage to the target material is different under different types of incident ion, which is not conducive to the radiation resistance comparison of the materials. Under the same irradiation conditions, the distribution of incident ions is consistent regardless of the increase in irradiation dose, but irradiation damage is accumulated until saturation. Among these six substances, zirconium oxide and zirconium carbide have better radiation resistance. The irradiation properties of zirconium oxide were verified by carbon ion irradiation experiments for tungsten alloy reinforced by zirconium oxide at 700 °C.

Abstract:Four kinds of tungsten-based materials, W-0.5 wt.%ZrC-(1, 3) wt.%Re (WZC1R, WZC3R) and W-0.5 wt.%HfC-(1, 3) wt.%Re (WHC1R, WHC3R), were prepared by mechanical ball milling and spark plasma sintering (SPS). The microstructures, mechanical properties and thermal stability were investigated. The WZC3R alloy exhibits a high ultimate tensile strength (UTS) of 728 MPa at 500 °C and an UTS of 653 MPa at 600 °C, respectively, which are about 2.1 times higher than SPSed pure W. The uniformly distributed nano-sized ZrC and HfC particles can pin the grain boundaries and dislocations, thereby increasing the strength and inhibiting grain coarsing. The WHC3R exhibits a total elongation (TE) of 13.9% at 400 °C, and its DBTT is in the range of 300 ~ 400 °C, which is about 200 and 300 °C lower than that of SPSed W-ZrC and pure W, respectively. The addition of the solid solution element Re improves the toughness of W materials by increasing the number of available slip planes and reducing the critical stress needed to start plastic deformation. In addition, the four alloys show excellent high-temperature stability with no significant change in grain size and Vickers microhardness even after heat treatments at temperatures reach up to 1600 °C. The Re element solidly dissolved in W leads to lattice distortion, which can inhibit the diffusion of W atoms at high temperatures, hinder the migration of grain boundary, and slow down the kinetic process of W grain coarsening, thus enhancing the high-temperature stability of the W materials.

Abstract:Niobium (Nb) is widely used in aerospace, nuclear energy and superconducting fields, due to its excellent comprehensive physical and chemical properties. In the preparation methods of the Nb coating, the molten salt electrodeposition technology has fast deposition rate, high cathode current efficiency and is suitable for complex shape components, which is expected to realize large-scale industrialized production and application. Since the current widely used fluoride-supported electrolyte system is highly toxic and environmentally unfavorable, there is an urgent need to carry out the development of a more environmentally friendly all chloride supporting electrolyte system. To achieve the regulation of the molten salt’s physical properties of the supporting electrolyte and the stabilization of the complexing ions, this study adds CsCl to the NaCl-KCl system to prepare an all chloride supporting electrolyte system and investigates the effect of CsCl on the molten salt’s physical properties of the supporting electrolyte and the electrodeposition behavior of the Nb coating. The results showed that the eutectic temperature of the NaCl-KCl-CsCl ternary mixed molten salt was about 485 °C. With the increase of CsCl content, the initial crystallization temperature of molten salt decreased at first and then increased, the density increased, and the conductivity and surface tension decreased. CsCl affected the mass transfer rate of ions in molten salt by changing the initial crystal temperature and conductivity of molten salt, and then affected the surface quality of electrodeposited Nb coating, and its preferred content was about 60 wt.%. The addition of CsCl can make the reduction potential of the oxygen-containing complex ion NbOF63- in the molten salt negative to that of NbF72-, which was helpful to obtain Nb coatings without oxygen impurities.

Abstract:In order to study the flow behavior of Mo-14Re molybdenum-rhenium alloy at high temperature and its cross-scale characterization, the high temperature compression test of molybdenum-rhenium alloy bar was carried out with Gleeble thermal simulation testing machine, and the selected temperatures were 1400 ℃, 1500 ℃ and 1600 ℃. The strain rates are 0.01 /s, 0.1 /s, 1 /s and 10 /s. The results show that when the strain rate sensitivity factor increases gradually, the plastic flow performance of the material will be better, and the two phenomena of stress hardening and softening exist simultaneously during deformation. On this basis, a cross-scale constitutive model is established. The flow stress characterization takes into account the resistance, thermal activation and grain boundary effects of the immobile dislocation. The microstructure evolution takes into account the grain size, dislocation density, dynamic recrystallization rate and crack volume fraction. The calculated values of yield stress, grain size and flow stress are in good agreement with the experimental results. It can be seen that the model can describe the rheological behavior and microstructure evolution of Mo-14Re molybdenum-rhenium alloy during high temperature deformation.

Abstract:Ammonium molybdate with lanthanum was prepared by centrifugaldrying, which was calcined to molybdenum trioxide with Lanthanum. The thermal decomposition of ammonium molybdate with lanthanum inairwasanalyzed by XRD and TG-MS, and the morphology and physicochemical properties of molybdenum trioxide with lanthanum were studied at different calcinationstemperature.The result shows that the structure of molybdenum trioxide with lanthanum is amorphous and microspheres withhollowspace inside. There were three stages in the process of the thermal decomposition of ammonium molybdate with lanthanum. Firstly, the centrifugaldrying powder changed from amorphous to crystalline states due to heat-treatment from room temperature to 196.5℃. Secondly, the residual ammonia ion in ammonium molybdate was decomposed from 196.5℃ to 337.8℃, and metastable molybdenum trioxide was formed, finally, metastable β-MoO3 turned into α-MoO3 from 337.8 ℃ to 410.1℃. Molybdenum trioxide with lanthanum prepared at different calcinedtemperature inherited the morphology of centrifugaldrying powder, with the increase of temperature, the surface of powder was coarser and thebreakageofpowder wasseriouser, and the internal small particles of powder changed from irregular and bonded to relatively regular flake. The change of calcinedtemperature had little effect on thecontentsof theimpurityelements in molybdenum trioxide with lanthanum, but with the increasing of calcinedtemperature, the apparent density and particle size reduced slightly.

Abstract:Molybdenum rhenium alloy has excellent mechanical and machining properties, and is a key structural material in fields such as electronics and nuclear industry. Adding zirconia to molybdenum rhenium alloy forms dispersion strengthening effect, and combined with deformation strengthening to improve the mechanical properties of the material. Research has found that the particle size of alloy powder decreases with the increase of ZrO₂ content, with the smallest and most uniform grain size at a content of 0.7%; ZrO₂ particles exhibit a pinning effect during the deformation and fracture process of the alloy, significantly improving its mechanical properties such as tensile strength, yield strength, and elongation after fracture. The tensile strength and elongation after fracture of ZrO₂ strengthened molybdenum rhenium alloy reach the highest value when the ZrO₂ content is 0.7%, and then decrease; ZrO₂ is basically dispersed at grain boundaries and forms a good bonding interface with the molybdenum matrix, which can inhibit the migration of grain boundaries and improve the deformation resistance of molybdenum alloys.

Abstract:_{:In this paper, the exploration and research of W-Ce alloys were carried out to prepare high density and high calorific value active alloys. Porous W skeleton was prepared by isostatic pressing with W powder as raw material. Then the skeleton was sintered to improve the skeleton strength. Finally, W-Ce alloy material with high density W as skeleton and active Ce as filling phase was prepared by liquid phase infiltration of Ce. The microstructure, properties and reactivity of W-Ce alloys prepared by different W skeleton preparation processes were studied. The results show that the density of W-Ce alloys is above 95 %. The phase composition of the alloy is W and Ce, and no intermetallic compound is formed. The dynamic compressive strength ranges from 621 MPa to 905 MPa, and the dynamic compressive plasticity ranges from 20 % to 30 %. The W-Ce alloy has a lower reaction threshold.}

Abstract:The flow behavior and microstructural evolution of a high-density Ni-42W-10Co-1Mo (wt.%) alloy were investigated at 1150-1300°C under strain rates of 0.001-1s_^-1 using a Gleeble-1500D. The results show that the initial microstructure was compsed of face-centered cubic matrix and σ phase. The flow stress was sensitive to the deformation temperature and strain rate, and the stress-strain curve showed a typical dynamic revertive softening characteristics deformated 1150°C, while typical dynamic recrystallization softening characteristics were observed deformed at 1200-1350°C. The Arrhenius equation was established based on the stress-strain curves, and the hot deformation activation energy of the Ni-42W-10Co-1Mo alloy was calculated to be 446.2 kJ/mol. The thermal processing map was constructed based on the dynamic material model to evaluate the thermal processing performance, and the instable zone was located at 1300°C under high strain rate. The deformation microstructureal evolution revealed that the dynamic recrystallization mechanism was discontinuous dynamic recrystallization, which preferentially nucleated around the σ phase. Finally, the optimized hot working window for Ni-42W-10Co-1Mo alloy was deformed at 1250-1300°C under strain rate of 0.1-0.01s_-1^.

Abstract:The influence of various heat treatment temperatures on the microstructural evolution and mechanical properties of the cold-rolled Ni42W10Co1Mo alloy was studied. The results indicated that the TCP phases transformed from σ phase to μ phase with the increase of heat treatment temperatures, and then transformed from μ phase to σ phase finnaly. The microstructure evolved from deformed dendrites to a uniform equiaxed grains. After heat treatment at 900°C, the precipitation phases are predominantly needle-like and blocky μ phases, with a small quantity of granular μ phases. Recrystallization was also evident. After heat treatment at 1200°C, a substantial amount of granular σ phases precipitated accompanying the completion of recrystallization. The extensive precipitation of TCP phases consumed a large amount of W element leading to a decrease of solid solution strengthening. The room temperature yield strength was decreased from 1564 MPa to 479 MPa after heat treatment at 1200°C, while, the elongation was enhanced to 72.4%. The precipitation of larger-sized μ phases was adversely to ductility, in contrast to the smaller-sized σ phases impeded crack propagation and enhcaned the ductility.

Abstract:Due to excellent properties such as high melting point, high strength, high hardness and high thermal conductivity, the molybdenum (Mo) and its alloys are widely used in aerospace, nuclear energy, electronics and chemical engineering. However, the material also has some inherent defects, such as insufficient high-temperature strength, low room temperature ductility, low recrystallization temperature and poor radiation resistance, etc. Various methods were researched to improve the material performances, and dispersed second phase particles is a simple and efficiency one. This article reviews the researches on the effects of different metal carbides and oxide strengthening phases on the microstructure and mechanical properties of Mo alloys. The influences of particle morphology, size distribution, volume fraction of oxides and carbides and interface structure with molybdenum matrix on the mechanical properties of molybdenum alloys were analyzed. The characteristics of different doping techniques to obtain high-performance molybdenum alloys were discussed, and the challenges and opportunities of dispersion strengthened molybdenum alloys in industrial applications and production were elaborated. This article aim to provide scientific basis for the design of dispersion strengthened molybdenum alloys, and expand the application of Mo alloys in various fields.

Abstract:Four-layer aluminum brazing sheets (4343/3003/6111/3003) with honeycomb sandwich structure are used as candidates for floor of high-speed train and ship deck, which are often exposed to corrosive environments. Microstructure and surface conditions of optimized 6111 aluminum alloy, which serves as the main support layer of this four-layer brazing sheet, have a great effect on the corrosion properties, which were investigated by a set of 6111 aluminum alloy ground with sandpaper of different grits. The results show that the AlFeSi(Mn, Cu) phase acts as cathode, due to its higher potential than that of the matrix, and forms a multi-stage system with adjacent matrix, which aggravates the surface corrosion. A smoother surface exhibits better corrosion resistance. Specifically, when lowering surface roughness from 18.03 μm to 0.92 μm, the surface volume decreases from 0.629 mm³ to 0.029 mm³, and the average number of intermetallic particles AlFeSi (Mn, Cu) is reduced from 1631 mm^-2 to 917 mm^-2, with area fraction decreasing from 3.93% to 0.92%. As a consequence, the average corrosion depth decreases from 237 μm to 95 μm.

Abstract:Solution treatment is a common heat treatment to improve the comprehensive properties of 7050 aluminum alloys. Due to the quenching sensitivity of 7050 alloy, the water quenching temperature is an important factor affecting its performance. Different water quenching temperatures affect the saturation of solid solution obtained consequently and the size of precipitated phases, which in turn affects the properties of the alloy. The effect of water quenching temperature on the microstructure and properties of 7050 aluminum alloy during solution treatment was investigated. Results show that with increasing the water quenching temperature, the fraction of high angle grain boundaries (HAGBs) in the alloy increases according to the EBSD analysis; dislocations are mainly concentrated in HAGBs and areas with dense grain boundaries (GBs); the precipitated phase of the alloy continuously forms and grows at the GBs; the hardness of the alloy shows a trend of increasing first and then decreasing; the corrosion resistance deteriorates as the water quenching temperature increases. The alloy shows excellent comprehensive properties when quenched in water at 50 °C, with a microhardness of 1707.16 MPa and a corrosion potential of ?0.927 V.

Abstract:Molten chloride salt is excellent candidature for third-generation solar energy storage media due to its good energy storage advantages and low price. However, in the actual working environment, molten chloride salt has strong corrosion to metal pipes (Inconel 625 alloy). Inconel 625 welding wire is usually used as a repair material for solar pipeline. In order to solve the problem of strong corrosion of molten chloride salt to Inconel 625 cladding metal, Inconel 625 cladding metal was welded by MAG welding, and the effect of nano-MgO particles and MgCl₂·6H₂O in-situ self-generated MgO on the corrosion of KCl-MgCl₂ molten salt was investigated. The results show that after 72 h of corrosion in KCl-MgCl₂, KCl-MgCl₂+5wt% MgO and KCl-MgCl₂+5wt% MgCl₂·6H₂O, the mass loss of Inconel 625 cladding metal is 0.00714, 0.00512, and 0.00308 g·cm^-2, respectively. The corrosion rate of Inconel 625 cladding metal in molten salt with in-situ self-generated MgO is decreased by 56.86% and 39.85%. Although the addition of nano-MgO particles in the molten salt can alleviate the corrosion of the chloride molten salt, the molten salt is agglomerated or settled, leading to a non-uniform distribution of MgO and MgCr₂O₄ protective shell layers. Adding MgCl₂·6H₂O to the molten salt can generate in-situ MgO, and the generated MgO and MgCr₂O₄ protective shells are more uniform, which hinder the erosion of corrosive media, so it is an effective method to reduce the corrosion of chloride molten salt.

Abstract:Ti/Al layered metal composites (LMCs) with 3, 5 and 7 layers were prepared via hot-pressing followed by hot-rolling at 500 °C. The crack initiation and growth behavior in LMCs during tensile and Erichsen cupping tests were explored. The influence mechanism of interface constraint on the mechanical performance and stamping formability of LMCs was analyzed. Results show that LMCs exhibit strong interfacial bonding due to intermetallic phase with micron-scale thickness. As the layers of LMCs increase, their yield strength (YS) and ultimate tensile strength (UTS) increase accompanied with the reduction in the elongation (EL) and toughness, and their anisotropy of mechanical performance increases obviously due to the strong basal texture formed by hot-rolling. Meanwhile, both the work-hardening exponent (n) and plastic strain ratio (r) decrease, but the yield strength ratio (σ_s/σ_b) increases, which deteriorates the stamping formability of LMCs. Interfacial delamination plays a crucial role in the fracture for LMCs with fewer layers. The interface is prone to delamination because of poor interfacial bonding, which delays the fracture failure of LMCs by inhibiting crack initiation, promoting crack deflection and passivation, and reducing the driving force of crack propagation.

Abstract:Self-designed induction coils, rigid restraint kits, and the existing laboratory induction heating apparatus were combined to conduct a local induction heating-based rigid restraint thermal self-compressing bonding (TSCB) treatment on a 5 mm-thick TC4 titanium alloy plate (the base metal), and the influence of holding temperature and heat treatment on the microstructure and mechanical properties of the joint was investigated. The results demonstrate that excessively low holding temperature (900 °C) results in insufficient atomic diffusion, while excessively high holding temperature (990 °C), exceeding the β→α phase-transition temperature, leads to the formation of coarse Widmanstatten microstructures, both of which contribute to the decrease in the mechanical properties of the joint. As the temperature increases, the pressure applied to the joint by the thermal constraint stress field initially rises and subsequently declines, so does the quality of the joint connection. Optimal mechanical properties are achieved only when the holding temperature is slightly below the β→α phase-transition temperature, specifically 950 °C, at which the microstructure distribution exhibits the highest level of uniformity, characterized by a significant presence of equiaxed α-phase grains. Additionally, the atomic diffusion is sufficiently enhanced, coupled with the highest pressure of the joint exerted by the stress field, resulting in the attainment of optimal mechanical performance. Upon annealing heat treatment at 650 °C for 3 h, the α→β phase-transition is observed, accompanied by a reduction in the degree of lattice distortion and grain refinement. The residual stress state of the TSCB joint transitions from tensile stress to compressive stress. The residual stress is significantly reduced, leading to stress relief. Consequently, the mechanical properties of the TSCB joint are improved, addressing the problem of low plasticity of the TSCB joint.

Abstract:This study focuses on the eutectic Al-14Cu-7Ce alloy to investigate the evolution of its microstructure and the changes in thermal conductivity and mechanical properties by adjusting the amount of Mg element added. The results show that the as-cast Al-14Cu-7Ce alloy is mainly composed of α-Al and Al8CeCu4 phases, with a microstructure consisting of coarse eutectic structure (α-Al + Al8CeCu4). The addition of a small amount of Mg element can refine the eutectic structure and improve its mechanical properties. With an addition of 1.0% Mg, the alloy"s yield strength and tensile strength increase to 164 MPa and 263 MPa, respectively, with an improvement of 29% and 19%. The elongation at break is enhanced to 4.5%, with an improvement of approximately 41%. The thermal conductivity is 130.2 W/(m·K), with a decrease of about 12%. As the Mg element is further increased to 2.0%, the mechanical properties of the alloy decrease, with the yield strength and tensile strength decreasing to 151 MPa and 249 MPa, respectively. The elongation at break decreases to 3.9%, and the thermal conductivity decreases to 108.3 W/(m·K). The decrease in thermal conductivity is mainly due to the solid solution of Mg atoms acting as scattering centers, hindering the movement of electrons within the lattice, and reducing the average free path of electrons and phonons. When the Mg content reaches 2.0%, the Mg reacts with Al and Cu elements to form the Al2MgCu phase, which is distributed in a fishbone-shaped eutectic structure (α-Al + Al2MgCu) at grain boundaries. This increases the volume fraction of the second phase in the alloy and further deteriorates its electrical and thermal conductivity. The decrease in mechanical properties of the alloy is mainly attributed to the presence of two eutectic structures, (α-Al + Al8CeCu4) and (α-Al + Al2MgCu), which increase the occurrence of microcracks at the phase interfaces. In summary, the addition of 1.0% Mg can obtain an Al-Cu-Ce eutectic alloy with high strength and high thermal conductivity.

Abstract:Based on XRD, XPS, H2-TPR and other characterization methods for physical and chemical properties and catalyst activity evaluation methods, the physical and chemical properties and catalytic activity of CDPF samples doped with different bimetal oxide under hydrothermal aging condition were studied. The results show that Ce-Zr bimetal oxide doped sample has good stability in phase structure and cell parameters, Zr-Fe bimetal oxide doped sample can better inhibit the dispersity of noble metal on carrier’s surface. For Fe-Ce and Zr-Fe bimetal oxide doped CDPF samples, during high-temperature aging process, the dispersed metal oxides undergo solid solution again, which will cause a formation of solid solution and more oxygen vacancies. After experiencing high-temperature hydrothermal aging process, the diffraction characteristic peaks of samples all migrate various degrees towards the high-temperature direction. Fe-Ce bimetal oxide doped sample shows a low degree of migration while Ce-Zr bimetal oxide doped sample is higher. Fe-Ce and Zr-Fe bimetal oxide doped aged samples showed higher oxidation activity of CO and show a low-level degradation. Ce-Zr bimetal oxide doped aged sample showed a slight decrease in the oxidation activity of C3H8. The catalytic activity for NO of Ce-Zr bimetal oxide doped sample decreases slightly after high-temperature hydrothermal aging process.

Abstract:The photoanode of QDSSCs was fabricated using industrially produced black titanium dioxide with stable yield and performance. Through comprehensive performance characterization and theoretical calculation studies, the photoanode was compared to common Anatase TiO2 and Rutile TiO2. Results indicate that the introduction of oxygen vacancies in Magonelli Ti8O15 leads to a decrease in conduction band bottom, shrinkage of band gap, and extension of absorption spectrum from ultraviolet to visible range.Key words: Titanium dioxide, Quantum dots, Solar cells, Magonelli Ti8O15

Abstract:The Gleeble-3800 thermal simulator was used to conduct isothermal constant strain rate thermal compression tests on TB15 titanium alloy to study its thermal deformation behavior at deformation temperatures of 810-930°C, strain rates of 0.001-10s-1 and height depression of 60%; three constitutive relationship models, physical, support vector regression (SVR) and response surface, were developed to predict the flow stresses of TB15 titanium alloy were predicted by three physical, support vector regression (SVR) and response surface constitutive models, and the prediction accuracy of the three constitutive models was compared. The results show that the flow stress of TB15 titanium alloy decreases with decreasing strain rate and increasing deformation temperature, and the change of peak stress is more sensitive to the strain rate; the correlation coefficient R of physical, SVR and response surface constitutive models are all greater than 0.98, but the R value of response surface constitutive model reaches 0.993, and the frequency of the relative error of the response surface constitutive models ±5% of the predicted value reached 67.9%, which was greater than that of the physical constitutive models at58.6%. The significance test value P<0.0001 of the constructed response surface constitutive model was also obtained by ANOVA, indicating that the regression relationship between the flow stress predicted by the response surface constitutive model and the deformation temperature, strain rate and strain was significant and had higher accuracy than the physical constitutive model and SVR constitutive model, which could better predict the flow stress of TB15 titanium alloy.

Abstract:With the increasing pollution of nitrogen oxides, the development of denitration catalysts have become one key factor for the treatment. In this paper, Ni0.09Ti0.91O2 nanotube supported copper denitration catalysts were prepared by hydrothermal and calcination two-step methods. The structure and catalytic denitration performance were studied. Results showed that the nanotube structure of the catalysts were determined by N2 adsorption-desorption, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and other methodologies. Ni0.09Ti0.91O2 nanotubes are anatase structures, copper atomic clusters are distributed on the surface of the nanotubes, and nitrogen adsorption and desorption tests determined that the specific surface area of Ni0.09Ti0.91O2 before and after loading copper was 263.51 and 216.5422 m2 g-1，respectively. The copper on the surface of the nanotubes was uniformly dispersed. The denitration efficiency of Ni0.09Ti0.91O2 nanotube with 7wt% copper was quite approach to 100%, which was higher than that of the nanotube catalyst without copper, and it had good anti-poisoning performance. The results of in-situ infrared spectroscopy diffuse reflection tests showed that the NH3-SCR process of Ni0.09Ti0.91O2-loaded copper followed the L-H mechanism. In this paper, the denitration performance of Ni0.09Ti0.91O2 nanoparticle-supported copper was also studied as a comparison. The catalyst of Ni0.09Ti0.91O2 nanotube loaded with 7wt% copper showed the best denitrification and anti-poisoning properties, which had good application prospects.

Abstract:TiO2 anode has received wide attention because of its good structural stability and safety during the charging and discharging of lithium-ion battery. However, the inherent poor conductivity of TiO2 limits its capacity and cycling stability at high current densities. In this paper, coaxial indium tin oxide-TiO2 nanotube complexes (ITO-TiO2NTs) were successfully prepared by vacuum mechanical press injection method and subsequent annealing treatment. As an anode material for Li-ion batteries, ITO-TiO2NTs exhibited a high capacity of 295.9 mAh g-1 after 350 cycles with a current density of 0.2 A g-1. The ITO acts as a conductive core in the three-dimensional structure, which improves the overall conductivity and facilitates the fast electron and Li-ion transfer, thus improving the cycling stability and multiplicity performance of the composite. The vacuum mechanical press injection method proposed in this paper provides a simple and efficient method for composite modification of TiO2 nanotube array thin film materials, which is of great significance.

Abstract:In this paper, Zn-3Cu alloy is taken as the research object. The effects of rolling deformation on the microstructure, mechanical properties and corrosion resistance of Zn-3Cu alloy were studied. It is found that with the increase of rolling deformation, the grain refinement of Zn-3Cu alloy matrix is deepened, and the CuZn5 phase in the alloy is elongated and partially broken along the rolling direction. The strength of Zn-3Cu alloy increases first and then decreases, and the plasticity increases continuously. The Zn-3Cu alloy with 60 % deformation has the highest yield strength, reaching 263.1 ± 4.9 MPa. With the increase of deformation, the corrosion resistance of the as-rolled Zn-3Cu alloy gradually decreases, and the as-cast Zn-3Cu alloy exhibits excellent corrosion resistance.

Abstract:In this paper, 8μm stainless steel fiber felt was used as raw material, and the stainless steel fiber porous material were prepared by volume-weighing method and high temperature sintering with different porosity, average pore size and thickness. Positive gradient structure, inverse gradient structure and film composite structure were designed by structural optimization. The sound insulation performance of the three kinds of the structures was tested, and the sound insulation characteristics of the structures were studied respectively. The sound insulation results indicate that the stainless steel fiber porous material has a certain sound insulation performance. The thickness is 20 mm, the porosity is 85 %, and the average sound insulation of the stainless steel fiber porous material is 18.92 dB in the frequency range of 50 ~ 6400 Hz. The lower the porosity, the smaller average pore size, the thicker the thickness, the better the sound insulation performance of the material; The sound insulation performance of the designed positive gradient and the inverse gradient structures is worse than the single layer stainless steel fiber porous material. The sound insulation performance of the stainless steel fiber porous composite material with film material is greatly improved at medium and high frequencies. The thickness is 20 mm, the average sound insulation is 27.86 dB, and the highest is increased by 16.96 dB.

Abstract:TC21 alloy has high strength and fracture toughness, however, the mechanism of crack initiation and propagation during impact is not clear, and the relationship between impact toughness and tensile properties is yet to be studied. In this work, different microstructures are prepared by regulating the solid solution temperature and cooling rate to study the tensile and impact properties. The results show that tensile performance and impact toughness exhibit different variation laws. The impact toughness of the bimodal structure with better plasticity is lower than that of the full lamellar structure with the worst plasticity, indicating that the intrinsic control mechanisms of tensile properties and impact toughness are different, which is further confirmed by the post-aging properties (no significant change in plasticity but significant decrease in impact toughness after aging). During tensile deformation, plastic deformation occurs in the whole region of the specimen before necking occurs, and the coordination deformation between α_p and β_t in the bimodal structure is fully developed, while the full lamellar structure has a larger colony size and its internal lamellar α orientation is uniform, and the dislocation slip length is larger, making it susceptible to plastic strain localization, resulting in a poorer strength plasticity matching than that of the bimodal structure. Under the influence of high strain rate, the crack initiation and propagation at the notch root are rapid, and the plastic deformation is concentrated in a small range near the crack tip, resulting in the coordination deformation between α_p and β_t cannot be fully played. In this case, the colony interface of the full lamellar structure has little influence on the plastic deformation, and the lamellar α and β become the control units of plastic deformation. The coarse lamellar α/β has better plastic deformation ability, resulting in higher crack initiation energy, contrary to the poor plasticity exhibited by stretching. In addition, the large angle interface of α colony causes the deflection of cracks and forms a tortuous path, resulting in higher impact toughness than the bimodal structure.

Abstract:Titanium and its alloys, characterized by light weight, excellent corrosion resistance, high strength, low elastic modulus, superior biocompatibility, and outstanding osseointegration, have become one of the mostly widely used metallic materials in aerospace and biomedical fields. However, their relatively low plasticity, hardness, and wear resistance constrain further development and applications. Laser surface treatment (LST) technology, which enhances surface properties without altering the bulk material, has emerged as a beneficial approach to modify the surface of titanium alloys. The research advancements and current applications of LST in surface modification of titanium and its alloys were reviewed. The mechanisms, process parameters, surface characteristics, and microstructures of various LST methods were analyzed, including laser transformation hardening (LTH), laser surface remelting (LSR), laser shock peening (LSP), laser surface alloying (LSA), laser cladding (LC), and composite LST techniques. The applications of LST in aerospace and medical domains were also clarified, as well as existing limitations, future research directions, and insights into the developmental trends of LST for titanium and its alloy materials. The objective is to advance LST innovation and to pave new avenues for the application of titanium alloys in various sectors.

Abstract:Magnesium alloys offer a lot of potential in the biomedical fields, due to their suitable elastic modulus for human bone, spontaneous degradability, and excellent biocompatibility, while low absolute tensile or yield strength and barren plastic abilities at room temperature significantly restrict their applications. As a successful method of enhancing mechanical properties, the hot deformation process can not only refine the grain sizes and broken sediments, but also introduce the high-density dislocations and change the texture orientation to improve the strength and plasticity. Based on the microstructure evolution laws, the latest research progress of Mg-based alloys under various hot deformation processes was reviewed. The differences in the deformation methods of rolling, forging, extrusion, and high-pressure torsion were compared. Under various hot deformation methods, the mechanism of grain refinement and the impact of dynamic recrystallization and dislocation propagation on the mechanical properties of Mg alloys were discussed. In addition, the relationships between microstructure and mechanical properties of hot-deformed Mg alloys were summarized.

Abstract:Co-based Heusler alloy is a kind of intermetallic compound with highly ordered crystal structure. Its chemical composition is usually expressed by Co2XY, where X is a transition metal element and Y is a main group element. Compared with other materials, it has higher spin polarizability, higher Curie temperature and lower damping factor. Based on these excellent characteristics, Co-based Heusler alloy has great application prospects in spin valves, tunnel junctions and semiconductor spin field effect transistors. This article reviews recent international studies on Co-based Heusler alloys on perpendicular magnetic anisotropy and spin-orbit torque. We summarized the influencing factors of perpendicular magnetic anisotropy and spin-orbit torque from the aspects of alloy composition, microstructure, magnetic layer thickness, buffer layer material, oxide layer material, element diffusion, etc. Which will help us better understand its deep-seated physical mechanism, as well as the challenges and prospects in future research.

Abstract:With outstanding comprehensive performance at high temperature, Nickel-based single crystal superalloy is the preferred material for aero-engine turbine blades, vanes and other components to withstand challenging service environment subjected to high temperature and intense stress. At present, various complex cooling structures are often used in the design of high-efficiency cooling blades to enhance blade temperature tolerance, among which the micro-cooling structure represented by lamilloy and double wall cooling are the main trend. However, the existence of ultra-thin wall structures in these complex turbine blades has become critical aspect and challenge in blade manufacturing. This paper provided an overview of the development trends in thin-walled structure of Ni-based single-crystal superalloys, analyzed the defects arising from thin-walled constrained space and the law of dendrite growth, elaborated the influence of thin-walled structure on mechanical properties and provided a prospect on advanced turbine blades preparation and development trend of its microstructure regulation.

Abstract:In order to synthesize high performance nickel-rich cathode, it is necessary to adopt favorable calcination temperature, calcination time and cooling procedure to lithiate hydroxide precursor, so as to form cathode material with better crystal structure and grain morphology in a controlled way. However, due to the large number of parameters involved in the calcination process, it is still challenging to reasonably design the calcination process which is required for preparing nickel-rich positive electrode with ideal structure and morphology. Therefore, it is necessary to deeply understand the evolution and formation rule of the phase, structure and morphology of intermediate during high temperature calcination, so as to provide reference for the design of nickel-rich cathode calcination process and directional control of structure. In this paper, the phase composition changes of precursor during the lithiation are briefly introduced from the point view of thermodynamic phase equilibrium. Secondly, the reaction mechanism and phase evolution of the intermediate are introduced based on in situ testing and theoretical calculation analysis. Then, the surface reconstruction phenomenon which is occurred in cooling process and significantly affects the properties of nickel-rich cathode materials is introduced, and the reasons for surface reconstruction are summarized. Finally, the morphology evolution and factors that affect the morphology during lithiation are introduced. Finally, the problems in the calcination process of nickel-rich cathode are discussed. The structural evolution and regulation of intermediate during high temperature lithiation process introduced in the paper could provide reference for relevant professionals to develop nickel-rich cathodes.

Abstract:Electrochromic materials have important application prospects in energy-saving windows, smart displays, and military camouflage protection, as they can stably and reversibly change their optical properties under an external electric field. By using multi-component synergistic methods, electrochromic devices can integrate more functions or new features, making them develop towards the direction of multifunctional integration and further expanding their application fields. In this article, we comprehensively review the latest research results on the functional design of electrochromic devices in the past decade, discussing their integration mode, working mechanism, and design strategies. We elucidate their application prospects in smart windows, energy storage devices, sensors, and military camouflage, and analyze in detail the key problems and major challenges that functional electrochromic devices face. We also propose new solutions and development directions, which are of great significance for guiding the research on the functionalization of electrochromic devices.