Sn对Al-Pb偏晶合金凝固过程及组织的影响  

EFFECT OF Sn ON THE SOLIDIFICATION PROCESS AND MICROSTRUCTURE OF Al-Pb MONOTECTIC ALLOYS

作　　者：陈书[1] 赵九洲[1] 

机构地区：[1]中国科学院金属研究所,沈阳110016

出　　处：《金属学报》2014年第5期561-566,共6页Acta Metallurgica Sinica

基　　金：国家自然科学基金项目51071159;51271185和51031003资助~~

摘　　要：研究了添加第三组元Sn对定向凝固Al-Pb合金组织的影响.结果表明,添加微量Sn能降低Al-Pb合金液-液相变时两液相间的界面能,促进富Pb相液滴形核和弥散型Al-Pb合金凝固组织的获得;随着Sn添加量的增加,弥散相体积分数增大,液-液相变温度区间和液-液-固三相温度区间之和增大,初生弥散相粒子和偏晶反应弥散相粒子的尺寸均增大;添加Sn促进Al-Pb合金中凝固界面枝晶化,这一方面促进弥散相液滴/粒子沿凝固方向均匀分布,另一方面,促进弥散相液滴/粒子沿定向凝固合金晶界分布.When a homogeneous, single-phase liquid of monotectic alloy is cooled into the miscibility gap, the components are no longer miscible and two liquid phases develop. Generally, the liquid-liquid decomposition causes the formation of the microstructure with serious phase segregation. Many efforts have been made to use the demixing phenomenon for the production of well dispersed composite materials. It has been demonstrated that the rapid directional solidification technique is an effective method to prevent the formation of the phase segregated mi- crostructure in immiscible alloys. Directional solidification experiments were carried out to study the influence of the addition of Sn on the solidification process of A1-Pb alloys. The experimental results show that the addition of a small amount of Sn causes a decrease in the interface energy between the matrix and the minority phase liquids and, thus, an increase in the nucleation rate of the minority phase droplets during the liquid-liquid phase transforma- tion or a decrease in the average size of the minority phase particles. With the increase of the Sn content, both the volume fraction of the minority phase droplets and the temperature range of the liquid-liquid phase zone and the liq- uid-liquid-solid tertiary phase zone of the phase diagram increase. These are favorable for the coarsening of the mi- nority phase droplets. The addition of Sn leads to the formation of a dendrite solid/liquid interface. This may pro- mote the formation of a well dispersed microstructure and shows great effect on the distribution of the minority phase particles.

关 键 词：AL-PB合金 偏晶合金 定向凝固 

分 类 号：TG113.2[金属学及工艺—物理冶金]