Influence of heat treatment on the microstructural evolution of CoCrFeNi high-entropy alloy prepared by Selective Laser Melting
C.H. Yang, Bo Huang, Yongjian Zheng, Jiehua Li, Hao Zhang, Yaoyao Ding, Liwen Liang, Zixiang Qiu, Haixuan Wang, Yang Yang, Miao Tian, Qizhong Huang, Zhining Wu, Jan Boháček
Abstract
The CoCrFeNi high entropy alloy (HEA) is widely used in aerospace and nuclear industries due to its excellent performance. However, traditional manufacturing methods make manufacturing parts with complex structures difficult. In this study, CoCrFeNi high-entropy alloys were prepared by the Selective Laser Melting (SLM) method, and their microstructures and mechanical properties with different annealing heat treatments lasting from 3 min to ∼ 1440 min were investigated. The surface of the constructed CoCrFeNi HEA alloys displayed typical SLM microstructures and morphologies. With increasing the heat treatment time, the melt pool boundary gradually disappeared within 10 min. The microstructure quickly changed from the original fine columnar crystals to long ellipsoidal grains, and the grain boundaries became more susceptible to etching after heat treatment. The crystals developed slowly in the next 20 h. According to the EBSD results, the un-heat-treated SLM HEA samples exhibit <101> texture along the build direction, the grains grow significantly after heat treatment, and the texture changes in the build direction. The microhardness values of the CoCrFeNi high-entropy alloys decrease with the increase in heat treatment time.