356铝合金凝固形核过程及液相线半连续铸造组织的研究  

Study on the Nucleating Process and Liquidus Semi-solid Casting Microstructures of Al 356

作　　者：董杰[1] 路贵民[1] 崔建忠[1] 

机构地区：[1]东北大学EMP教育部重点实验室,辽宁沈阳110006

出　　处：《铸造》2001年第12期720-723,共4页Foundry

基　　金：国家自然科学基金资助项目 (599740 0 9)

摘　　要：本文研究了 35 6铝合金在液相线温度附近等温形核过程和激冷组织变化情况 ,在液相线以上温度 ( 62 5℃ ) ,熔体激冷形核数量相对较少 ,初晶相晶粒尺寸较大 ,单位面积数目较少 ;在略低于液相线的温度 ( 612℃ )保温 30min ,熔体大量形核 ,初晶相晶粒细小球化 ,单位面积数目较大 ;在液相线以下温度 ( 60 0℃ ) ,熔体形核数量多 ,但部分合并长大 ,初晶相晶粒为细小的枝晶 ,单位面积晶粒数较小。通过液相线半连续铸造对形核机理进行了验证 ,熔体在液相线温度 ( 615℃ )保温 30min后铸造 ,获得了均匀、细小的近球形晶粒组织 ,平均晶粒尺寸小于 40 μm 。The nucleating process and the variation of the chilling microstructures were studied when 356 alloy was held at the temperature near its liquidus in this paper. From the temperature (625℃) above liquidus, the melt had little nucleation. The primary grains were big and the number of grains per area was little. From the temperature (612℃) slightly under its liquidus, the nucleation number was most in the melt, the primary grains were fine and global, the number of grains per area was more, and the optimum holding time was near 30min at 612℃. From the temperature (600℃) below its liquidus, the nucleation number was more, but some nucleuses congregated and grew dendritically. The 'Liquidus Semi solid Casting' was used to validate the nucleating mechanism. When the alloy melt was semi continuously cast after being held for 30min at the liquidus temperature (612℃), the as cast microstructures, average diameter of which was smaller than 40μm, were fine, uniform, near global and very suitable for thixoforming.

关 键 词：铝合金 形核 液相线铸造 半固态铸造 凝固组织 

分 类 号：TG292[金属学及工艺—铸造] TG249