W-30Cu纳米复合粉末液相烧结致密化与晶粒长大机制  

Densification and Grain Growth Mechanism of Nanosized W-30Cu Powder during Liquid Phase Sintering

作　　者：郭垚峰[1] 范景莲[1] 刘涛[1] 

机构地区：[1]中南大学粉末冶金国家重点实验室,湖南长沙410083

出　　处：《稀有金属材料与工程》2014年第1期125-129,共5页Rare Metal Materials and Engineering

基　　金：国家杰出青年科学基金(50925416);国家自然科学基金(50874122)

摘　　要：采用喷雾干燥-煅烧、还原工艺制备超细W-30Cu复合粉末,将粉末模压成形,在1340～1420℃液相烧结15～120min,研究其致密化行为及晶粒长大机制。结果表明:W-30Cu复合粉末在液相烧结早期发生了显著的致密化,1340℃烧结15 min致密度可达到90%以上;随烧结时间的延长致密度增加,1380℃烧结90 min相对密度达到99.1%。液相烧结过程中,W晶粒不断长大并逐渐球化,且其晶粒大小G与烧结时间t符合G3∝kt关系,服从液相烧结溶解-析出机制。烧结温度对W晶粒长大影响显著,当温度从1340℃上升到1420℃时,其晶粒长大动力学系数从1.61×10-2μm3/min增大到4.65×10-2μm3/min,液相的形成、颗粒重排、溶解-析出及W晶粒长大使细晶W-Cu获得近全致密。W-30Cu composite powder fabricated by sol-spray drying and subsequent hydrogen reduction was pressed and directly liquid phase sintered at 1340-1420 ℃ for 15-120 min, the densification and grain growth mechanism were studied. The results show that the significant densification occurs in the early sintering stage of the liquid phase. When sintered at 1340 ℃ for 15 min, the relative density reaches above 90%. With the sintering time increases, the relative density increases. When sintered at 1380 ℃ for 90 min, the maximum relative density of 99.1% is obtained. During liquid sintering, W grains grow up as spherical shape, and the grain size G and sintering time t matches the relationship G3 kt, which means that the grain growth of W is subjected to the dissolution-precipitation mechanism. When sintered in the range of 1340-1420 ℃, the grain growth kinetic coefficients increase from 1.61× 10-2 to 4.65×10-2μm3/min. The results suggest the formation of liquid, particle rearrangement, dissolution-precipitation and grain growth cause nano-sized W-30Cu composites to reach nearly full density.

关 键 词：W-30Cu 液相烧结 致密化 晶粒长大 

分 类 号：TF124.54[冶金工程—粉末冶金]