超细晶粉末冶金CoCrFeMnNiGd0.15高熵合金的组织性能

Microstructure and Mechanical Properties of Ultrafine-grained CoCrFeMnNiGd0.15 High-entropy Alloy Fabricated by Powder Metallurgy

摘要:

采用机械合金化和放电等离子烧结的方法制备出超细晶CoCrFeMnNiGd_0.15合金,研究了CoCrFeMnNiGd_0.15高熵合金的组织与性能。结果表明,其组织为多相结构,基体为FCC固溶体相,析出相为稀土氧化物(Gd₂O₃)和富Gd、Ni、Mn的四方结构相。随着烧结温度的提高,析出相的含量不断增加且尺寸不断增大,合金的压缩屈服强度不断下降而塑性则不断上升。在900℃烧结时材料具有最优的综合力学性能,其压缩屈服强度(σ_0.2)、抗压强度(σ_max)、断裂时的塑性应变(ε_p)和维氏硬度分别达到1662 MPa、2518 MPa、30.6%和458 Hv。

Abstract:

The Ultrafine-grained CoCrFeMnNiGd_0.15 high-entropy alloy (HEA) was prepared by mechanical alloying (MA) and spark plasma sintering (SPS). The microstructure and mechanical properties of CoCrFeMnNi Gd_0.15 high-entropy alloy was investigated. It was found that the sintered CoCrFeMnNiGd_0.15 alloy showed a multi-phase microstructure including the FCC matrix, a rare earth oxide (Gd₂O₃) and a tetragonal phase rich in Gd, Ni and Mn element. As the sintering temperature increased, the content and size of the precipitated phase increased continuously, the compressive yield strength of the alloy decreased while the plasticity showed the opposite trend. The sintered alloy achieved the best comprehensive mechanical properties at the sintering temperature of 900 °C, with a compressive yield strength of 1662 MPa, compressive strength of 2518 MPa, plastic strain of 30.6% and Vickers hardness of 458 Hv. With the increase of temperature, the fracture morphology of compressive specimens consisted of fine equiaxed dimples, the diameter and depth of the dimples increased continuously and some tearing ridges were observed.