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摘要: 采用热压烧结和放电等离子烧结的方法制备了Ta-W-Si合金，利用X射线衍射分析、扫描电子显微镜观察、背散射电子成像及能谱分析等手段研究了合金的显微结构和相组成，并讨论了烧结方式和硅质量分数对合金烧结致密化和硬度的影响。结果表明，两种烧结方式烧结后的样品相对密度均达到了96%以上，可以实现致密化，硅元素的添加有利于合金的致密化；扫描电子显微观察和背散射电子成像显示合金中出现两种不同区域，物相分析存在Ta-W与Ta3Si两相；硅元素的添加有利于提高合金硬度，硅化物第二相强化、细晶强化和晶界区的氧化富集是强化的主要机制。Abstract: The Ta-W-Si alloys were prepared by hot pressed sintering and spark plasma sintering. The microstructure and phase composition of sintered alloy were investigated by XRD (X-ray diffraction), SEM (scanning electron microscopy), BSE (backscattered electron imagine), and EDS (energy dispersive spectrum), and the influences of sintering method and silicon content by mass on densification and hardness were analyzed. The results show that, the relative density of alloy prepared by two sintering methods reaches over 96%, and the addition of silicon element is benefited to the densification of alloy. Two different regions can be found in SEM and BSE images, which are identified as Ta-W and Ta3Si by XRD pattern. Hardness increases clearly with the addition of silicon element. The primary strengthening mechanisms are the second-phase strengthening of silicides, the grain refinement strengthening, and the oxidative concentration in grain boundary region.
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图 1 Ta–10W–1.5Si合金X射线衍射图谱：（a）热压烧结；（b）放电等离子烧结
Figure 1. XRD patterns of Ta–10W–1.5Si alloy: (a) hot pressing sintering; (b) spark plasma sintering
图 2 Ta–10W–1Si合金烧结前粉末的热重–示差扫描量热曲线
Figure 2. TG–DSC curve of Ta–10W–1Si powder before sintering
图 3 Ta–10W–1Si原料粉末1450 ℃加热后X射线衍射图谱
Figure 3. XRD patterns of Ta–10W–1Si powder after heated at 1450 ℃
图 4 Ta–15W–1.5Si合金扫描电子显微形貌：（a）热压烧结；（b）放电等离子烧结
Figure 4. Scanning electron microscope images of Ta–15W–1.5Si alloy: (a) hot pressed sintering; (b) spark plasma sintering
图 5 热压烧结Ta–15W–1.5Si合金的背散射电子显微镜图像
Figure 5. Backscattered electron microscope image of Ta–15W–1.5Si alloy by hot pressed sintering
表 1 Ta–W–Si合金原料的化学成分和配比组成
Table 1. Chemical composition and component of Ta–W–Si raw material
编号 配比组成 化学成分（质量分数）/% Si W Ta A Ta–10W–0.5Si 0.5 10 其他 B Ta–10W–1.0Si 1.0 10 其他 C Ta–10W–1.5Si 1.5 10 其他 D Ta–15W–1.5Si 1.5 15 其他 E Ta–20W–1.5Si 1.5 20 其他 F Ta–10W 0 10 其他 G Ta–15W 0 15 其他 H Ta–20W 0 20 其他 
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表 2 粉末冶金法制备合金的密度
Table 2. Density of alloy prepared by powder metallurgy
编号 名称 理论密度/(g·cm-1) 热压烧结相对密度/% 放电等离子烧结相对密度/% A Ta–10W–0.5Si 16.60 99.10 ― B Ta–10W–1.0Si 16.30 99.07 99.59 C Ta–10W–1.5Si 16.01 99.30 99.17 D Ta–15W–1.5Si 16.11 99.13 ― E Ta–20W–1.5Si 16.22 99.14 97.82 F Ta–10W 16.91 98.70 96.69 G Ta–15W 17.03 98.58 ― H Ta–20W 17.15 97.63 96.35
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表 3 热压烧结法制备Ta–W–S合金的维氏硬度
Table 3. Vickers hardness of Ta–W–S alloy prepared by hot pressed sintering
编号 名称 维氏硬度，HV /GPa 平均值 方差 A Ta–10W–0.5Si 5.33~6.09 5.67 0.23 B Ta–10W–1.0Si 5.61~6.56 6.04 0.33 C Ta–10W–1.5Si 6.06~6.87 6.48 0.29 D Ta–15W–1.5Si 6.60~7.15 6.90 0.21 E Ta–20W–1.5Si 6.78~7.46 7.05 0.23 F Ta–10W 4.30~4.69 4.53 0.16 G Ta–15W 3.91~4.30 4.06 0.14 H Ta–20W 3.91~4.43 4.17 0.15
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表 4 放电等离子烧结法制备Ta–W–S合金的维氏硬度
Table 4. Vickers hardness of Ta–W–S alloy prepared by spark plasma sintering
编号 名称 维氏硬度，HV/GPa 平均值 方差 A Ta–10W–0.5Si ― ― ― B Ta–10W–1.0Si 6.24~7.13 6.72 0.31 C Ta–10W–1.5Si 5.88~6.94 6.46 0.40 D Ta–15W–1.5Si ― ― ― E Ta–20W–1.5Si 6.02~6.99 6.32 0.32 F Ta–10W 3.87~4.11 3.98 0.09 G Ta–15W ― ― ― H Ta–20W 3.46~3.84 3.68 0.13
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