粉末冶金FeCoNiCu0.4Al0.4高熵合金的热处理组织与性能

Microstructure and mechanical properties of heat treated FeCoNiCu0.4Al0.4 high entropy alloy prepared by powder metallurgy

采用机械合金化(MA)与放电等离子烧结(SPS)相结合的方法制备出FeCoNiCu0.4Al0.4高熵合金,研究不同热处理温度对合金显微组织与力学性能的影响规律。结果表明:机械合金化后,FeCoNiCu0.4Al0.4高熵合金形成了单相的FCC固溶体,经1100℃SPS烧结后的块体组织仍为单相FCC结构,其压缩屈服强度、塑性应变和显微硬度分别为1165.1 MPa、45.2%和356.9 HV。经过热处理后,合金组织中生成了新的BCC相,且BCC相的含量随热处理温度的升高先增多后减少,500、600和700℃热处理后BCC相的含量分别为7%、30%和21%(体积分数)。退火态FeCoNiCu0.4Al0.4高熵合金的屈服强度随热处理温度的升高先升高后降低。当BCC相含量增多时,材料的屈服强度和硬度相应地提高,而塑性却显著降低。

The mechanically alloyed(MA)FeCoNiCu0.4Al0.4 high-entropy alloy(HEA)powders were sintered by spark plasma sintering(SPS)at temperature of 1100℃ and subsequently heat-treated at different temperatures.The microstructural evolution and mechanical properties of heat-treated HEAs were investigated.The results show that only a supersaturated face-centered cubic(FCC)structured solid solution forms during MA process.After sintering,the bulk FeCoNiCu0.4Al0.4 HEA also has a single FCC structure.The compressive yield strength,plastic strain and micro-hardness of sintered HEA are 1165.1 MPa,45.2% and 356.9 HV,respectively.BCC phase is precipitated from the FCC matrix during heat treatment process.The volume fractions of BCC phase in samples heat-treated at 500,600 and 700 are 7%,30% and 21%,respectively.The yield strength first increases and then decreases with the increase of heat treatment temperature.When the BCC phase fraction increases,the yield strength and hardness of HEA increase while the plasticity decreases obviously.