(1. 中南大學(xué) 粉末冶金國(guó)家重點(diǎn)實(shí)驗(yàn)室，長(zhǎng)沙 410083；
2. 南車戚墅堰機(jī)車車輛工藝研究所有限公司，常州 213011)
摘 要: 采用溶膠−噴霧干燥及氫還原工藝制備超細(xì)/納米W-20 Cu復(fù)合粉末；將粉末壓制成形，在1 340~1 420 ℃燒結(jié)5~180 min，并研究其致密化行為及晶粒長(zhǎng)大機(jī)制。結(jié)果表明：燒結(jié)溫度對(duì)液相燒結(jié)致密化起主要作用，W-20Cu復(fù)合粉末在液相燒結(jié)早期發(fā)生了顯著的致密化，在1 420 ℃燒結(jié)5 min時(shí)，致密度可達(dá)到89%以上；隨燒結(jié)時(shí)間的延長(zhǎng)，致密度增加，在1 420 ℃燒結(jié)90 min時(shí)，相對(duì)密度最高，達(dá)到99.1%。液相燒結(jié)時(shí)，W晶粒不斷長(zhǎng)大并逐漸球化，且其晶粒大小G與時(shí)間燒結(jié)t符合 關(guān)系，服從溶解−析出機(jī)制。燒結(jié)溫度對(duì)W晶粒長(zhǎng)大影響顯著，當(dāng)溫度從1 340 ℃上升到1 420 ℃時(shí)，其晶粒長(zhǎng)大動(dòng)力學(xué)系數(shù)從1.59×10−2 μm3/min增大到2.47×10−2 μm3/min，這說明液相的形成、顆粒重排、溶解−析出及W晶粒長(zhǎng)大使得細(xì)晶W-Cu坯體獲得近全致密。
關(guān)鍵字: 超細(xì)/納米W-20Cu；燒結(jié)機(jī)制；晶粒長(zhǎng)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
