Effect of sintering temperature on the microstructures and properties of 93W-4.9Ni-2.1Fe alloy by spark plasma sintering
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摘要: 以高能球磨法制備的93W-4.9Ni-2.1Fe復合粉末為原料,采用放電等離子燒結技術制備93W-4.9Ni-2.1Fe合金,研究了燒結溫度對鎢合金微觀組織及性能的影響.采用掃描電鏡對試樣的斷口進行觀察,采用能量色散譜儀對合金的組元進行成分分析.結果表明:①燒結溫度對合金的性能有顯著的影響,在1 350℃時鎢合金的抗拉強度達到一個極大值,為981 MPa,此時鎢合金的相對密度和W晶粒的尺寸分別為98.9%和5μm;②當燒結溫度達到1375℃時,合金中Ni元素開始揮發,隨著溫度的快速上升,合金中Ni元素的揮發不斷加劇,當燒結溫度升高至1425℃時合金中Ni元素已完全揮發;③合金的斷裂方式隨著燒結溫度的升高發生顯著的變化,當燒結溫度升至1350℃時鎢合金的斷裂方式由W晶粒界面分離向W-W、W-黏結相界面斷裂轉變,而當燒結溫度超過此溫度時鎢合金的斷裂方式又轉變為W晶粒的沿晶脆性斷裂;④SPS快速燒結能夠有效抑制W晶粒的長大,促進鎢合金的細晶強化作用.Abstract: 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.
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Key words:
- tungsten alloys /
- spark plasma sintering /
- temperature /
- microstructure /
- mechanical properties
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