Microstructures and mechanical properties of laser-directed energy deposited CrCoNi medium-entropy alloy  

作　　者：Wen-Jie Zhao Chang-Yu Liu Peng-Cheng Che Zhi-Liang Ning Hong-Bo Fan Jian-Fei Sun Yong-Jiang Huang Alfonso H.W.Ngan 

机构地区：[1]National Key Laboratory for Precision Hot Processing of Metals,Harbin Institute of Technology,Harbin 150001,China [2]Space Environment Simulation Research Infrastructure,Harbin Institute of Technology,Harbin 150001,China [3]Department of Mechanical Engineering,The University of Hong Kong,Hong Kong 999077,China

出　　处：《Rare Metals》2024年第7期3286-3300,共15页稀有金属（英文版）

基　　金：financially supported by the funding from Guangdong Province Basic and Applied Research Key Projects (No.2020B0301030001);National Key R&D Programme,Ministry of Science and Technology of China (Nos. 2018YFB1105200 and 2019YFA0209904);the National Natural Science Foundation of China (Nos.52371106 and 52371025)。

摘　　要：The distinctive intrinsic heat treatment(IHT)originating from cyclic reheating in the laser-directed energy deposition(LDED) has attracted growing attention in recent years.In this investigation,simulations and experimental characterizations were performed to examine the impact of IHT on the micros true ture and mechanical properties of LDED-fabricated CrCoNi medium-entropy alloy(MEA).The results show that the intensity of the IHT is proportional to the utilized laser energy density(LED).As the LED increased,significant dynamic recrystallization and grain refinement occurred within the alloy due to the enhanced intensity of IHT.However,the high LED leads to severe hot cracking within the as-built MEA,resulting in inferior ductility.By decreasing LED,the hot cracking was effectively eliminated.Meanwhile,low LED weakened the intensity of IHT and consequently inhibited kinetic conditions of dynamic recrystallization,resulting in a heterogeneous grain structure characterized by multi-scale-sized grains.This structure provides significant hetero-deformation-induced hardening during plastic deformation,enabling the alloy to have a sustainable work-hardening capacity.We expect that this work will have implications in taking full advantage of the unique IHT of the LDED process to fabricate ME As with excellent metallurgical quality and mechanical performance.

关 键 词：Intrinsic heat treatment Laser-directed energy deposition CrCoNi MEA Dynamic recrystallization Heterogeneous grain structure 

分 类 号：TP391.73[自动化与计算机技术—计算机应用技术] TG139[自动化与计算机技术—计算机科学与技术]