Al/Ti/Ta合金化对CoCrNi中熵合金结构与性能的影响OA

Through introducing three kinds of Al/Ti/Ta elements into the CoCrNi medium-entropy alloy,and combining with vacuum arc melting,a series of(CoCrNi)99.5-2x(AlTi)xTa0.5 medium-entropy alloys(MEAs)have been fabricated to investigate the effects of codoping with Al(atomic fraction,at.%)(1,3,5,7),Ti(atomic fraction,at.%)(1,3,5,7),and Ta(0.5at.%)on microstructural evolution and mechanical properties of the CoCrNi medium-entropy alloys.The results indicate that the inducing of Al/Ti/Ta can prompt brittle precipitate phases to generate within the ductile CoCrNi matrix.The precipitation of secondary hard phases can significantly enhance the room-temperature compressive strength and hardness without significantly decreasing the fracture strain of the CoCrNi medium-entropy alloy.Specifically,the(AlTi)7Ta0.5 alloy exhibits an excellent strength-ductility balance,achieving a compressive yield strength of approximate 1.0 GPa and a hardness of HV470,respectively,while maintaining a high fracture strain of 23.6%.Microstructural characterizations reveal that the precipitation strengthening and solid solution strengthening are primary causes of the increment in yield strength and hardness.