定向凝固制备工艺对CoCrFeNiMnx高熵合金组织结构和压缩性能的影响

    Effects of Directional Solidification Preparation Process on Microstructure and Compressive Properties of CoCrFeNiMnx High Entropy Alloy

    • 摘要: 采用真空电弧熔炼法和定向凝固法制备CoCrFeNiMnxx=0.25,0.75)高熵合金,研究了定向凝固法对其微观组织演化和压缩性能的影响。利用金相显微镜(OM)、扫描电镜(SEM)观察合金的微观组织,采用X射线衍射仪(XRD)、能谱仪(EDS)对合金的相组织和成分进行分析,采用万能试验机测试合金的压缩性能。结果表明,相比于电弧熔炼法制备的合金,该系合金经定向凝固后,其微观结构由单一的FCC1结构转变为FCC1+FCC2混合结构;且合金晶粒择优生长,晶粒尺寸增大,微观组织形貌由树枝晶转变为等轴枝晶。定向凝固后,CoCrFeNiMn0.25合金的抗压强度由1905 MPa减小至1810 MPa,表现出较好的压缩延展性。

       

      Abstract: CoCrFeNiMnx (x=0.25, 0.75) high entropy alloys were prepared by vacuum arc melting and directional solidification, and the effects of directional solidification process on its microstructure evolution and compressive properties were studied. The microstructure of the alloys was observed by optical microscope (OM) and scanning electron microscope(SEM), the phase structure and composition of the alloys were analyzed by X-ray diffractometer (XRD) and energy dispersive spectrometer (EDS), and the compressive properties of the alloy were tested by universal testing machine. The results show that, compared with the alloy prepared by arc melting, the microstructure of the alloy changes from a single FCC1 structure to a mixed FCC1+FCC2 structure after directional solidification. Moreover, the alloys grains grow preferentially, the grain size increases, and the microstructure morphology changes from dendrite to equiaxial dendrite.After directional solidification, the compressive strength of CoCrFeNiMn0.25 alloy decreases from 1905 MPa to 1810 MPa, and the compressive strain is better.

       

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