结晶初期熔体流动对半固态合金粒状初晶形成的作用  

EFFECT OF MELT FLOW AT INITIAL SOLIDIFICATION ON GRANULAR PRIMARY CRYSTAL FORMATION IN SEMI-SOLID ALLOY

作　　者：潘冶[1] 张春燕[1] 袁浩扬[1] 孙国雄[1] 

机构地区：[1]东南大学机械工程系,南京210018

出　　处：《金属学报》2001年第10期1035-1039,共5页Acta Metallurgica Sinica

基　　金：高等学校骨干教师计划[2000]65;教育部留学回国人员基金[1998]679;东南大学科学基金 K97015

摘　　要：采用控制熔体结晶法制得颗粒状组织半固态 ＺＬ１０１合金，研究了结晶初期熔体流动对粒状初晶形成的作用．结果表明：粒状晶的形成除受浇铸温度影响外，还与熔体充型方式有关．常用的上铸充型可使初生α相粒化，而充型平稳的底铸所得组织仍以树枝晶为主．６８０℃浇铸后自然凝固组织为树枝状；相同条件下，在液相线温度附近对熔体施以极短时的搅动，便得到粒状α组织．数值模拟揭示了熔体充型及结晶初期温度和流速的变化，液相线温度附近的熔体流动是粒状晶形成的关键．Semi-solid ZL101 alloy with granular microstructures has been successfully produced by controlled crystallization, and the effect of melt flow at initial solidification on granular primary phase formation is analyzed. The granular crystal formation depends on the mold filling ways of the melt besides pouring temperature. The upper filling can make the primary a phase granulated, while the bottom filling makes it dendritic in a large number of areas. The dendrites appear in the solidified ingot cast from 680 degreesC. Attractively, the alpha phase can be granulated by stirring the melt nearby liquidus for very short time under the above cast condition. The numerical simulation describes temperature and velocity field of the melt in mold filling and at initial solidification. It is shown that the melt flow nearby liquidus plays an important role in formation of the granular phase formation.

关 键 词：半固态加工 熔体流动 数值模拟 ZL101合金 半固态合金 铝合金 

分 类 号：TG146.21[一般工业技术—材料科学与工程] TG249[金属学及工艺—金属材料]