真空烧结制备90W­Ni­Fe高密度钨合金的性能与显微结构

摘要

采用真空烧结法制备90W­7Ni­3Fe 高密度钨合金，通过材料试验机、SEM、XRD 等表征了材料的性能与显微结构。结果表明：钨合金的相对密度、强度、塑性均随烧结温度升高先上升后下降，1440℃烧结试样的性能最佳，其相对密度、抗弯强度、抗拉强度、伸长率和断面收缩率分别为99.2%、1920.5 MPa、1086.7 MPa、22.8%和24.4%。钨合金单纯由体心立方的钨相和面心立方的Fe3Ni2固溶体相组成，未出现其他杂质相。在1360~1460℃的烧结温度范围内，随温度的升高，钨合金断裂形态依次发生以下转变：沿晶脆性断裂、穿晶脆性断裂、韧窝韧性断裂、粘接相撕裂韧性断裂和穿晶脆性断裂。%90W­7Ni­3Fe high­density tungsten alloys were fabricated by vacuum sintering method. Material testing machine, SEM and XRD were adopted to characterize the performance and microstructure of the alloys. The results show that the relative density, strength and plasticity of tungsten alloys increase at first and decrease afterwards with the increase of the sintering temperature. The sample sintered at 1 440℃demonstrates the optimal performance. Its relative density, bending strength, tensile strength, elongation and cross section shrinkage ratio are 99.2%, 1 920 MPa, 886 MPa, 22.83%and 24.37%, respectively. The tungsten alloy is simply made up of body centered cubic tungsten phase and face centered cubic Fe3Ni2 solid solution phase. With the increase of sintering temperature, the fracture morphology of tungsten alloy is transformed from intergranular brittle fracture to transgranular brittle fracture, dimple ductile fracture, bonding phase tearing ductile fracture and transgranular brittle fracture subsequently during the sintering temperature range from 1 360 to 1 460℃.