Microstructure and properties of annealed MoCrFeMnNi high entropy alloys

Abstract

Abstract: High entropy alloys have attracted extensive attention due to their high strength, corrosion resistance and high temperature oxidation resistance. In our research, a high-entropy alloy MoCrFeMnNi was prepared by aluminothermic reaction method. Microstructures and properties of 700 ℃/12 h, 800 ℃/6 h, 1 000 ℃/3 h annealed alloys were investigated respectively by XRD, SEM, EDS, microhardness test and compression experiment. The results show that the high entropy alloy MoCrFeMnNi prepared by the aluminothermic method has typical dendritic morphology, and the crystal structure is mainly composed of BCC phase, FCC phase and a small amount of dispersion phase. The dendritic region is BCC structure, rich in Mo and Cr elements. The interdendritic region is FCC structure, rich in Ni element. With the increase of annealing temperature, the nanoscale σ phase is gradually precipitated between dendrites, leading to the increase of alloy hardness, which may reach up to 667 HV and 1 050 MPa after annealing at 800 ℃/6 h. After annealing at 1 000 ℃/3 h, the σ phase agglomerates into a spherical and acicular shape and is partially dissolved at high temperature. With decrease of σ phase, the hardness of the alloy decreases, the compressive strength is equal to that of as-cast state, and the plasticity of the alloy is significantly improved.

Key words: aluminothermic reaction, high entropy alloy, annealing, microstructure

CLC Number:

TG146

LA Pei-qing, WANG Jiao, XIAO Hai-bo, ZHENG Yue-hong, YANG Li-jie, SHENG Jie. Microstructure and properties of annealed MoCrFeMnNi high entropy alloys[J]. Journal of Lanzhou University of Technology, 2020, 46(5): 1-6.

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