选区激光熔化成形CoCrFeNiCuAl_(0.8)高熵合金的组织与性能

Microstructure and Properties of Selective Laser Melting Formed CoCrFeNiCuAl_(0.8) High Entropy Alloy

采用选区激光熔化成形(SLM)技术制备CoCrFeNiCuAl_(0.8)高熵合金,研究了不同激光热输入(0.06~0.36J·mm^(-1))下合金的成形质量和密度,确定最优成形工艺参数,并分析了在最优成形工艺参数下合金的显微组织和拉伸性能。结果表明:随着热输入的增加,SLM成形合金的密度先增大,当热输入大于0.15J·mm^(-1)时,密度基本保持不变;当热输入为0.34J·mm^(-1)时,密度最大,为7.5g·cm^(-3),最优工艺参数为激光功率270W、扫描速度800mm·s^(-1)。SLM成形合金具有由无序体心立方相(A2相)和有序体心立方相(B2相)组成的双相结构,显微组织由柱状晶和等轴晶组成,屈服强度、抗拉强度、断后伸长率、断面收缩率分别为651MPa,840MPa,22%,23%,断裂机制为韧性断裂。

CoCrFeNiCuAl_(0.8)high entropy alloy was prepared by selective laser melting(SLM).The forming quality and density of the alloy at different laser heat inputs(0.06-0.36J·mm^(-1))were studied,and the optimal forming process parameters were determined.The microstructure and tensile properties of the alloy under the optimal forming process parameters were analyzed.The results show that the density of SLM formed alloy increased first with the increase of heat input,and basically remained unchanged when the heat input was largerthan0.15J·mm^(-1).When the heat inputwas0.34J·mm^(-1),the alloy had the maximum densityof7.5g·cm^(-3),and the optimal process parameters were as follows:laser power of 270Wand scanning speed of 800mm·s^(-1).The SLM formed alloy had a dual-phase structure consisted of disordered body-centered cubic phase(A2phase)and ordered bodycentered cubic phase(B2phase),and the microstructure was composed of columnar and equiaxed grains.The yield strength,tensile strength,percentage elongation after fracture and percentage reduction of area of the alloy were 651MPa,840MPa,22%and 23%,respectively.The fracture mechanism was ductile fracture.