Effect of scanning speeds on mechanical properties of CoCrNi medium entropy alloy prepared by laser additive manufacturing

Medium entropy alloy (MEA) is a hot spot in the field of material research in recent years. At present, the most widely used processing method of MEAs is "casting-rolling-heat treatment", and the preparation of CoCrNi MEA by laser additive manufacturing (LAM) is still in primary stage. In this study, CoCrNi MEAs were fabricated with different scanning speeds by laser additive manufacturing, and the influence of scanning speed on its mechanical properties was investigated. The results show that higher scanning speed can significantly improve the mechanical properties of CoCrNi MEA. Compared with the low-speed laser additive manufacturing (LSLAM) MEA, the tensile strength of high-speed laser additive manufacturing (HSLAM) MEA is increased by 5.6 % and the fracture strain is increased by 60 %, which is mainly due to the entanglement of 1/6<112> and 1/2<110> dislocations and the defect structure at the grain boundary. LAM is a promising technology that can promote the development and application of MEAs in industry.