铸态CoCrNiCu_(x)中熵合金的组织和力学性能研究

Study on Microstructure and Mechanical Properties of As-cast CoCrNiCu_(x)Medium Entropy Alloys

采用真空电弧炉制备了不同摩尔比的CoCrNiCu_(x)(x=0,0.4,0.8,1.0)中熵合金,对铸态CoCrNiCu_(x)合金微观结构、相组成以及力学性能进行分析。研究CoCrNiCu_(x)合金的组织与性能随Cu含量变化的变化规律。结果表明:CoCrNiCu_(0)合金晶体结构为单一FCC相,随着Cu含量的增加,合金由单一FCC相转变成FCC1相和富铜FCC2相组成的组织结构。合金组织形貌为树枝状,FCC2相的生成使得合金的微观组织从粗大树枝晶转变成细小的树枝晶。加入Cu后,合金的屈服强度和屈强比分别从234.1 MPa、0.368增加至353.1 MPa、0.715;而断后伸长率降低,从x=0时的88.0%降低至x=1.0时的30.1%。随合金中Cu含量的增加,合金的显微硬度呈增加趋势,最大值为190.58 HV。

CoCrNiCu_(x)(x=0,0.4,0.8,1.0)medium entropy alloys with different molar ratios were prepared by using vacuum electric arc furnace,and the microstructure,phase composition and mechanical properties of CoCrNiCu_(x) alloys were analyzed to find out the variation pattern of the microstructure and properties with the change of Cu content.The results show that the crystal structure of CoCrNiCu_(0) alloy is a single FCC phase,with the increase of Cu content,the alloy transforms from a single FCC phase to the microstructure composed of FCC1 phase and copper-rich FCC2 phase.The microstructure of the alloy is dendritic,and the formation of FCC2 phase makes the microstructure of the alloy change from bulky dendrites to fine dendrites.After adding Cu,the yield strength and yield ratio of the alloy increase from 234.1 MPa and 0.368 to 353.1 MPa and 0.715,respectively.The elongation at break decreases from 88.0%at x=0 to 30.1%at x=1.0.The microhardness of the alloy shows an increasing trend with the maximum value of 190.58 HV.