合金半固态组织的影响
(1.康佳集团股份有限公司，深圳 518053；
2.清华大学 土木工程系，北京 100084；
3.吉林大学南岭校区 材料科学与工程学院，长春 130025；
4.东南大学 机械工程系，南京 210096)
摘 要: 过共晶Al-17%Si-4.5%Cu-0.5%-Mg合金通过Sr优化变质处理获得初晶硅细小且有α枝晶的显微组织。在固液两相区保温，结合金相分析研究组织的转变规律，结果表明：共晶硅经历着熔断、粒状化和粗化的过程，初晶硅有长大的趋势；随着保温时间的延长，共晶体不断熔化成液相，液相体积分数逐渐增加，直至液相薄膜包围着α相，α相由不规则形状向球状转化，α相的粗化和合并几乎同时进行，最终获得非常理想的半固态组织。从形状系数和等效直径两个方面评价了近球形α相的特征。
关键字: 半固态；过共晶铝硅合金；二次加热；近球形α 相
method on semi-solid microstructure of
hypereutectic Al-Si alloy
（1. Konka Group Co., LTD.，Shenzhen 518053，China；
2. Department of Civil Engineering，Tsinghua University，
Beijing 100084，China；
3. College of Materials Science and Engineering，
Jilin University，Nanling Campus，Changchun 130025，China；
4. Department of Mechanical Engineering，Southeast University，
Nanjing 210096，China）
Abstract:Microstructures with fine primary Si and a number of dendrite α phases were obtained by Sr optimizing modification. Microstructure evolution during partial reheating through the liquidus-solidus range was investigated by optical metallography. Eutectic Si experiences the course of dissolution, granular and coarsening, and the primary Si has a tendency of growth. With the extending of isothermal holding times, the eutectic melts d own partially, and the liquid content increases gradually up until liquid film surrounds α phases. α phases tend to be changed into sphericity. The coarsening and bending of α phases go on homogeneously. The sphere-like α phases obtained are quantitatively characterized by shape factor and equivalent diameter.
Key words: semi-solid; hypereutectic Al-Si alloy; partial reheating; sphere-like α phases
