(中南大学 粉末冶金国家重点实验室， 长沙 410083)
摘 要: 以喷雾干燥-H2还原法制备的纳米级90W-7Ni-3Fe复合粉末为原料, 研究了不同稀土Y含量对试样烧结特性的影响, 采用扫描电镜和金相仪器分别对断口进行了形貌观察和W晶粒粒度测试； 并对烧结样的相对密度、 抗拉强度、 延伸率等性能进行了测定与分析。 研究结果表明： 不添加稀土Y时， 试样在液相烧结时容易出现孔洞和气泡, 导致试样力学性能偏低； 当添加稀土Y后, 烧结样中没有孔洞和气泡, 添加0.4％~0.6%稀土Y（质量百分数）时, 合金相对密度、 抗拉强度和延伸率分别为99.6%、 1 080 MPa和17.6%； 添加0.4%Y后, W晶粒从原来的20~25 μm减小到10~12 μm, W晶粒由不加稀土时的球形变为近球形或多边形, 且随稀土含量的增加其影响作用更明显； 在相界或晶界上形成了W13.07Ni2.96Fe1.52Y23.65Ox(摩尔比)的中间相, 阻止了W原子在粘结相中的扩散及W晶粒的长大。 建立了合金中W颗粒的三层微观结构模型。
关键字: 90W-7Ni-3Fe合金； 纳米级粉末； 稀土Y； 烧结特性
（ State Key Laboratory of Powder Metallurgy,
Central South University, Changsha 410083, China）
Abstract: Nanosized 90W-7Ni-3Fe composite powder synthesized by spray drying-H2 reduction method was used as raw material. Effects of sintering characteristics for specimens were studied by adding different contents of Y. Fracture morphology and W crystal sizes were measured by scanning electron microscopy and optical microscopy, respectively. Relative density, tensile strength and elongation of sintering specimens were also measured and analyzed. The results show that the emergence of cavities and vapour inner sintering specimens leads to low mechanical properties during liquid phase sintering with no addition of Y. Cavities and vapour in sintering specimens disappear when adding some Y. When the Y addition is 0.4%-0.6%, the relative density, tensile strength and elongation of alloy are 99.6%, 1 080 MPa, 17.6%, respectively. Average W crystal size decreases from 20-25 μm to 10-12 μm by adding 0.4% Y, and the W crystal morphology is nearly spherical or polyhedron. The higher the rare earth addition is, the bigger influence on W crystal morphology is. Middle phase W13.07Ni2.96Fe1.52Y23.65Ox (mole ratio) appears at interface when rare earth Y is added, which decreases the diffuse of W atom in matrix phase and prevents W crystal from growing up. The three layer microstructure model image of W particle inner alloy was established.
Key words: 90W-7Ni-3Fe alloy； nanometer powder； rare earth Y； sintering properties
