SPS烧结温度对93W-4.9Ni-2.1Fe合金微观结构及性能的影响

以高能球磨法制备的93W-4.9Ni-2.1Fe复合粉末为原料,采用放电等离子烧结技术制备93W-4.9Ni-2.1Fe合金,研究了烧结温度对钨合金微观组织及性能的影响.采用扫描电镜对试样的断口进行观察,采用能量色散谱仪对合金的组元进行成分分析.结果表明:①烧结温度对合金的性能有显著的影响,在1 350℃时钨合金的抗拉强度达到一个极大值,为981 MPa,此时钨合金的相对密度和W晶粒的尺寸分别为98.9%和5μm;②当烧结温度达到1375℃时,合金中Ni元素开始挥发,随着温度的快速上升,合金中Ni元素的挥发不断加剧,当烧结温度升高至1425℃时合金中Ni元素已完全挥发;③合金的断裂方式随着烧结温度的升高发生显著的变化,当烧结温度升至1350℃时钨合金的断裂方式由W晶粒界面分离向W-W、W-黏结相界面断裂转变,而当烧结温度超过此温度时钨合金的断裂方式又转变为W晶粒的沿晶脆性断裂;④SPS快速烧结能够有效抑制W晶粒的长大,促进钨合金的细晶强化作用.

Effect of sintering temperature on the microstructures and properties of 93W-4.9Ni-2.1Fe alloy by spark plasma sintering

A 93W-4.9Ni-2.1Fe heavy alloy was prepared by spark plasma sintering with 93W-4.9Ni-2.1Fe composite powders synthesized by high energy ball milling as raw materials,and the influences of sintering temperature on its microstructure and properties were studied.The fracture morphology and composition of the alloy were measured by scanning electron microscopy and energy dispersive spectrometry,respectively.It is shown that the properties of samples change significantly with sintering temperature,and the tensile strength appears a peak of 981 MPa at 1 350℃,where the relative density and the W crystalline grain size arrive at 98.9% and 5 μm,respectively.Ni element in samples tends to volatilize when the sintering temperature reaches 1 375℃,and it is completely volatilized when the sintering temperature hits 1 425℃.The fracture mode of the alloy sintered from 1 250℃ to 1 350℃ changes from W-W cleavage to tungsten-matrix fracture,while it transforms into W-W cleavage again beyond 1 350℃.Grain growth can be effectively inhibited by spark plasma sintering,which prompts fine grain strengthening of the alloy.