不同时效温度结合深冷处理工艺对AlCoCrFeNi2.1共晶高熵合金微观组织及力学性能的影响OA

Taking the AlCoCrFeNi2.1 eutectic high entropy alloy as the subject investigated,the effects of aging and deep cryogenic composite heat treatment on the phase compositions,the microstructures and the mechanical properties were systematically explored.The strengthening mechanisms for the alloys under three different heat treatment processes were elucidated.The results show that after aging at 700℃alone or aging at 700℃followed by cryogenic treatments,the alloys all present lamellar eutectic structures of FCC phases alternating with B2 phases.Deep cryogenic treatment promotes the generation of dislocations in FCC phases and the precipitation of BCC coherent nanophases in B2 phases,which improves the strength and plasticity of the alloy simultaneously.After aging at 900℃and deep cryogenic treatment,the B2 phase transforms to FCC phase,and BCC nanophases grow abnormally,and the alloy elongation reaching the highest value of 27.2%,but the tensile strength decreasing.The coherent nano precipitates generated after deep cryogenic treatment can act as the sources for the dislocation activation,significantly increasing the number of mobile dislocations and effectively dispersing internal stress concentrations within the alloy,in turn improving the plastic deformation capacity of the alloy.