热处理对Al_(0.5)CoCrFeNiTi_(0.15)高熵合金微观组织和性能的影响

Effect of heat treatment on microstructure and properties of Al_(0.5)CoCrFeNiTi_(0.15)high-entropy alloy

采用真空电弧熔炼法制备了Al_(0.5)CoCrFeNiTi_(0.15)高熵合金,研究热处理对其微观组织、力学性能和耐腐蚀性能的影响。结果表明:热处理后Al_(0.5)CoCrFeNiTi_(0.15)高熵合金的组织仍为典型的枝晶结构,即FCC+BCC结构,热处理并未改变合金的相组成,表明合金具有良好的热稳定性;随着热处理温度升高,合金的共晶组织先细化后变粗。当在800℃热处理6 h后,由于合金共晶组织的细化和点状组织的析出,使得合金拥有最高的硬度、屈服强度和极限强度,分别为420.2 HV0.2、1130.71 MPa和2548.43 MPa。热处理可有效改善合金的耐腐蚀能力,其中800℃热处理6 h时具有最高的破钝电位和最宽的钝化区。

Al_(0.5)CoCrFeNiTi_(0.15)high-entropy alloy was prepared by vacuum arc melting method,and the effect of heat treatment on its microstructure,mechanical properties and corrosion resistance was studied.The results show that the microstructure of the Al_(0.5)CoCrFeNiTi_(0.15)high-entropy alloy after heat treatment still exhibits a typical dendritic structure,namely FCC+BCC structure.The heat treatment does not change the phase composition of the alloy,indicating that the alloy has good thermal stability.As the heat treatment temperature increases,the eutectic structure of the alloy first refines and then coarsens.After heat treatment at 800℃for 6 h,due to the refinement of the eutectic structure and the precipitation of the point-like structure,the alloy has the highest hardness,yield strength and ultimate strength,which are 420.2 HV0.2,1130.71 MPa and 2548.43 MPa,respectively.Heat treatment can effectively improve the corrosion resistance of the alloy,with the highest passivation potential and widest passivation resistance observed after heat treatment at 800℃for 6 h.