Al0.8CrFe2Nix高熵合金的组织与力学性能

Microstructure and Mechanical Properties of Al0.8CrFe2Nix High Entropy Alloys

采用真空电弧熔炼法制备了Al0.8CrFe2Nix高熵合金(x为Ni与Cr的摩尔比),采用金相观察、X射线衍射、显微硬度检测和压缩试验等手段研究了Ni含量对其组织及力学性能的影响。结果表明,当x=0.50时,合金为B2+BCC晶体结构,组织为树枝晶+胞状晶;当x=1.25时,合金晶体结构转变为单一的BCC结构,而组织变为单一的树枝晶;当x=2.00时,合金转变为FCC+BCC的混合结构,其组织转变为细小密集的片层状共晶组织;随着Ni含量继续增加,当x=2.75时,合金保持着FCC+BCC结构,而FCC相比例明显增加,并形成了完整连贯的树枝晶组织;Al0.8CrFe2Nix高熵合金的硬度随x的增加而降低,同时屈服强度减小、韧性增加。

Al0.8CrFe2Nix high-entropy alloys(x denotes the atomic content of Ni element when the atomic content of Al, Cr and Fe is 0.8, 1 and 2, respectively) were prepared by vacuum arc melting. The effects of Ni content on microstructures and mechanical properties of the alloy were investigated by using optical microscope, X-ray diffraction(XRD), micro-hardness testing and compression testing. The results show that the alloy with dendritic+cellular crystal morphology has a B2+BCC crystal structure when x=0.50. When x=1.25, the crystal structure is transformed to single BCC with a single dendritic morphology. When x=2.00, the crystal structure is changed into a mixed structure of FCC+BCC with a dense lamellar eutectic-like morphology. With the further increase of Ni content, the alloy maintains FCC+BCC structure when x=2.75. However, the proportion of FCC phase is dramatically increased and complete dendritic morphology appears. The hardness of Al0.8CrFe2Nix high entropy alloys is decreased with the increase of x. Meanwhile, the yield strength is decreased and the strain is increased.