(1. 中南大学 粉末冶金国家重点实验室，长沙 410083；
2. 南车戚墅堰机车车辆工艺研究所有限公司，常州 213011)
摘 要: 采用溶胶−喷雾干燥及氢还原工艺制备超细/纳米W-20 Cu复合粉末；将粉末压制成形，在1 340~1 420 ℃烧结5~180 min，并研究其致密化行为及晶粒长大机制。结果表明：烧结温度对液相烧结致密化起主要作用，W-20Cu复合粉末在液相烧结早期发生了显著的致密化，在1 420 ℃烧结5 min时，致密度可达到89%以上；随烧结时间的延长，致密度增加，在1 420 ℃烧结90 min时，相对密度最高，达到99.1%。液相烧结时，W晶粒不断长大并逐渐球化，且其晶粒大小G与时间烧结t符合 关系，服从溶解−析出机制。烧结温度对W晶粒长大影响显著，当温度从1 340 ℃上升到1 420 ℃时，其晶粒长大动力学系数从1.59×10−2 μm3/min增大到2.47×10−2 μm3/min，这说明液相的形成、颗粒重排、溶解−析出及W晶粒长大使得细晶W-Cu坯体获得近全致密。
关键字: 超细/纳米W-20Cu；烧结机制；晶粒长大；溶解−析出
composite powder during liquid sintering
（1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
2. China Southern Locomotive and Rolling Stock Industry Group Qishuyan Institute Co., Ltd, Changzhou 213011, China）
Abstract:Ultrafine/nano W-20Cu (mass fraction, %) composite powders were synthesized by sol-spray drying and subsequent hydrogen reduction process. The powder compacts were sintered at 1 340−1 420 ℃ for 5−180 min. The densification and the mechanism of the grain growth were studied. The results show that, the sintering temperature is the main factor for the densification. The significant densification occurs in the early sintering stage in the liquid phase for W-20Cu composite powders. When sintered at 1 420 ℃ for 5 min, the relative density reaches above 89%. With the extension of the sintering time, the relative density increases. When sintered at 1 420 ℃ for 90 min, the maximum relative density of 99.1% is obtained. During liquid sintering, W grain becomes large and spherical, and the grain size G and time t match the relationship , which means that the grain growth of W is subjected to the dissolution-precipitation mechanism. As the sintering temperature increases, the grain growth kinetic parameters of W increase from 1.59×10−2 μm3/min to 2.47×10−2 μm3/min at 1 340−1 420 ℃. The formation of liquid, particle rearrangement, grain growth and dissolution-precipitation cause W-Cu material to reach nearly full density.
Key words: ultrafine/nano W-20Cu; sintering mechanism; grain growth; dissolution-precipitation
