功率超声对纯铝凝固组织的影响  

Effect of power ultrasonic treatment on solidification structure of pure aluminum melt

作　　者：何迁[1] 李建国[1] 何北星[1] 

机构地区：[1]清华大学材料科学与工程系,北京100084

出　　处：《轻合金加工技术》2008年第12期14-18,49,共6页Light Alloy Fabrication Technology

摘　　要：对1.5 kg的纯铝熔体进行了功率超声辅助凝固试验,研究了功率超声对不同纯度纯铝凝固组织的影响,并比较了机械搅拌与功率超声的细化效果。结果表明,功率超声可以有效细化w(Al)=99.7%工业纯铝以及w(Al)=99.992%高纯铝的凝固组织。功率超声与机械搅拌相比,所获得的凝固组织更均匀且不易产生铸造缺陷。基于结晶游离理论讨论了功率超声的细化机制。功率超声的空化作用促进了超声耦合头附近液面的异质形核,声流作用则促进了晶粒的游离和沉淀。此二者的综合效应是等轴晶区形成的主要原因。In this paper, sohdification of pure aluminum melt weighing 1.5 kg under power ultrasonic treatment（UST） was tested. And the effect of UST on solidification structure of aluminum melt with different purity was investigated. Besides, the grain refining effects of mechanical stirring and UST were compared. The results show that the UST was able to refine both the 99.7 % pure aluminum melt, and the 99.992% high purity aluminum melt. Compared to the mechanical stirring, the UST can bring out more homogeneous structure without casting defects. Furthermore, the mechanisms of the grain refinement by UST were analyzed. The cavitations stimulated the heterogeneous nucleation at the ultrasonic resonator, and the acoustic flows promoted the dispersion and the precipitation of the nuclei. These two processes were together considered as the main reason why the equiaxed zone was formed.

关 键 词：功率超声 纯铝 凝固组织 晶粒细化 细化机制 

分 类 号：TG146.21[一般工业技术—材料科学与工程] TG292[金属学及工艺—金属材料]