ZA27合金自孕育流变压铸显微组织及凝固行为  

Microstructure and solidification behavior of ZA27 prepared by self-inoculation rheological die casting

作　　者：邱谨[1] 李元东[1,2] 李明[1] 张继渊[1] 管仁国[1,3] 陈体军[1,2] 

机构地区：[1]兰州理工大学省部共建有色金属先进加工与再利用国家重点实验室,兰州730050 [2]兰州理工大学有色金属合金及加工教育部重点实验室,兰州730050 [3]东北大学材料与冶金学院,沈阳110004

出　　处：《中国有色金属学报》2017年第1期72-81,共10页The Chinese Journal of Nonferrous Metals

基　　金：国家自然科学基金资助项目(51464031)~~

摘　　要：采用自孕育法制备ZA27半固态浆料,研究流变压铸成形过程中的显微组织及凝固行为。结果表明:ZA27半固态浆料在480℃等温保温3 min,能够制备出细小、圆整、分布均匀的初生α(Al)晶粒,平均晶粒尺寸52.32μm。浆料在成形过程中发生液相偏析,在受力较大部位,二次颗粒长成"蠕虫状"。剩余液相在铸件不同部位的凝固方式不同,但都没有粗大的树枝晶存在。在冷却速率较小的部位,二次凝固方式主要为依附初生晶粒生长,在共晶组织中有包晶β相析出。在冷却速率较大部位主要为形核凝固,二次晶粒数目多,共晶组织细小。二次晶粒既能够以富Zn的α(Al)相形核,也可以直接以β相形核生长。Cu富集在共晶η相中。The semi-solid slurry of ZA27 casting alloy was prepared by self-inoculation method.And then,the microstructure and solidification behavior during rheo-diecasting forming process were studied.The results show that the semi-solid slurry of ZA27 alloy with the morphology of fine,round and uniform distribution of primary α（Al） grains can be prepared when the slurry is isothermally holded at 480 ℃ for 3 min,the average size of primary grain is 52.32 μm.Segregation of liquid phase would be occured during the forming process of semi-solid slurry,the secondary solidified grains grow into ＂vermicular＂ in the area of the high stress.Remaining liquid has different solidification ways in the different parts of castings,but without coarse dendrites.In the positions of low cooling rate,the peritectic phase （β） can be generated in eutectic microstructure,where the attachment growth is the mainly way for secondary solidification.On the contrary,in the position of high cooling rate,the mainly way is nucleation solidification with a lot of secondary crystal nucleus and the fine eutectic microstructure.The grains of secondary solidification can either nucleate by α（Al）,or grow directly by the nucleus ofβ phase.Cu element is enriched in the eutectic ηphase.

关 键 词：自孕育法 二次凝固 半固态 包晶 共晶 ZA27合金 

分 类 号：TG146.1[一般工业技术—材料科学与工程]