水下搅拌摩擦加工CoCrFeNiMn高熵合金微观组织及力学性能

Microstructure and mechanical properties of CoCrFeNiMn high-entropy alloy prepared by underwater friction stir processing

采用水下搅拌摩擦加工(UFSP)技术制备了细晶CoCrFeNiMn高熵合金,研究了细晶CoCrFeNiMn高熵合金的微观组织和力学性能。结果表明,经UFSP处理后,CoCrFeNiMn高熵合金试样的平均晶粒尺寸由母材的110μm细化至2.6μm,细晶内部出现大量孪晶,沿晶界析出少量BCC相。晶粒细化和BCC相的析出将细晶CoCrFeNiMn高熵合金的平均显微硬度由150 HV提高至310 HV,抗拉强度由349 MPa提高至938 MPa,分别达到母材的206%和269%。同时,孪晶协调了拉伸变形过程中试样应力的均匀分配,缓解了应力集中的出现。因此,细晶CoCrFeNiMn高熵合金表现出良好的伸长率。

Fine-grained CoCrFeNiMn high-entropy alloy was prepared by underwater friction stir processing(UFSP)technology.The microstructure and mechanical properties of fine-grained CoCrFeNiMn high-entropy alloy were studied.The results show that the average grain size of CoCrFeNiMn high-entropy alloy sample is refined from 110μm of base metal to 2.6μm after UFSP treatment.A large number of twins occur in fine grains,and a small amount of BCC phase is percipitated along grain boundary.The grain refinement and precipitation of BCC phase promote the average microhardness from 150 HV to 310 HV and tensile strength from 349 MPa to 938 MPa of the fine-grained CoCrFeNiMn high-entropy alloy,which reaches 206%and 269%of base metal,respectively.At the same time,twin coordinates the uniform distribution of stress of sample during tensile deformation and alleviates the occurrence of stress concentration.Therefore,fine-grained CoCrFeNiMn high-entropy alloy exhibits good elongation.