真空燒結制備90W-Ni-Fe高密度鎢合金的性能與顯微結構Performance and microstructure of 90W-Ni-Fe high-density tungsten alloy fabricated by vacuum sintering

采用真空燒結法制備90W-7Ni-3Fe高密度鎢合金，通過材料試驗機、SEM、XRD等表征了材料的性能與顯微結構。結果表明：鎢合金的相對密度、強度、塑性均隨燒結溫度升高先上升后下降，1 440 ℃燒結試樣的性能最佳，其相對密度、抗彎強度、抗拉強度、伸長率和斷面收縮率分別為99.2%、1 920.5 MPa、1 086.7 MPa、22.8%和24.4%。鎢合金單純由體心立方的鎢相和面心立方的Fe₃Ni₂固溶體相組成，未出現其他雜質相。在1 360~ 1 460 ℃的燒結溫度范圍內，隨溫度的升高，鎢合金斷裂形態依次發生以下轉變：沿晶脆性斷裂、穿晶脆性斷裂、韌窩韌性斷裂、粘接相撕裂韌性斷裂和穿晶脆性斷裂。

90W-7Ni-3Fe high-density 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 ℃.

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