7075 Al合金液相线半连续铸造组织及形成机理  

AS-CAST MICROSTRUCTURES AND THE SOLIDIFYING MECHANISM OF 7075 ALUNMINUM ALLOY CAST BY LSC

作　　者：路贵民[1] 董杰[1] 崔建忠[1] 常守威[1] 

机构地区：[1]东北大学材料与冶金学院,沈阳110004

出　　处：《金属学报》2001年第10期1045-1048,共4页Acta Metallurgica Sinica

基　　金：国家自然科学基金资助项目59974009

摘　　要：研究了液相线半连续铸造法制备 ７０７５ Ａｌ合金半固态浆料的组织．合金熔体在常规铸造温度（７２０℃）下浇注获得的锭坯边部是粗大的枝晶，中间部位组织极不均匀；在接近液相线温度（６４２℃）保温 ３０ ｍｉｎ后的铸造组织较好，中心部位和边部组织的差异较小．在液相线温度附近（６３８℃）保温后进行半连续铸造获得的锭坯中心和边部组织均是均匀、细小的近球形组织．　一次冷却强度的降低、二次冷却强度的增大和铸造速度的减小有利于均匀、细小的近球形组织的形成．熔体中大量内生形核和固－液界面成分过冷的降低有利于上述组织的形成．结果表明，液相线半连续铸造是一种有效的半固态浆料的制备方法．The observations of microstructures of 7075 alloy cast by liquidus semi-continuous casting (LSC) revealed that the border of billet cast from the normal temperature (720 degreesC) consists of coarse dendritics, and the center microstructure is very inhomogeneous. When the billet was cast from the temperature (642 degreesC) upside liquidus and the alloy melt was held for 30 min, the border and the center microstructures are good and the difference between them is small. When the billet was cast from the temperature (638 degreesC) closely near liquidus and the alloy melt was held for 30 min, the border and the center microstructures are the best and all consist of fine, uniform and globular grains. Decreasing the first cooling and the casting velocity and increasing the second cooling are helpful to the formation of fine, uniform and globular grains. The formation of the globular microstructures is related to a lot of nucleus produced form the inner alloy melt and reduction of the undercooling at solid/liquid interface. The results show that LSC is an efficient way for making semi-solid slurries.

关 键 词：液相线半连续铸造 半固态浆 组织 铝合金 

分 类 号：TG292[金属学及工艺—铸造] TG249.7