等温热处理对Mg-Gd-Zn-Zr合金半固态组织的影响  

Effect of isothermal heat treatment on semi-solid microstructure of Mg-Gd-Zn-Zr alloy

作　　者：尹健 卢春辉[2] 谢世坤 易荣喜 黄文先 Yin Jian;Lu Chunhui;Xie Shikun;Yi Rongxi;Huang Wenxian(School of Mechanical and Electrical Engineering,Jinggangshan University,Ji'an Jiangxi 343009,China;School of Aeronautical Manufacturing Engineering,Nanchang Hangkong University,Nanchang Jiangxi 330063,China;School of Building Engineering,Jinggangshan University,Ji'an Jiangxi 343009,China)

机构地区：[1]井冈山大学机电工程学院,江西吉安343009 [2]南昌航空大学航空制造工程学院,江西南昌330063 [3]井冈山大学建筑工程学院,江西吉安343009

出　　处：《金属热处理》2020年第2期175-181,共7页Heat Treatment of Metals

基　　金：国家自然科学基金(51661023);江西省自然科学基金(20181BAB206028);江西省教育厅科学技术研究项目(GJJ160732,GJJ160733)。

摘　　要：选择稍高于共晶反应温度作为等温热处理温度,对铸态Mg-15Gd-2Zn-0. 6Zr合金进行等温热处理,获得了半固态球化组织。研究了热处理温度和保温时间对半固态组织的影响,探讨了半固态组织演变机制及适用于低温等温热处理的半固态Mg-Gd-Zn-Zr合金成分设计。结果表明,液相组织具有低的温度敏感性,其组织演变主要机制为α-Mg表面熔化和α-Mg动态再析出,而固相颗粒球化机制为:α-Mg树枝晶→枝晶臂粗化→枝晶臂合并、不规则多边形化→球化。Semi-solid spheroidized microstructure was obtained by isothermal treatment on as-cast Mg-15 Gd-2 Zn-0. 6 Zr alloy at the temperature slightly higher than eutectic temperature. The effects of isothermal heat treatment temperature and holding time on semi-solid microstructure were studied,and the mechanism of semi-solid microstructure evolution and the composition design of semi-solid Mg-Gd-Zn-Zr alloy were discussed. The results show that the volume fraction of liquid phase has a low sensitivity to temperature. The mechanism of the liquid phase evolution is α-Mg surface melting and α-Mg dynamic precipitation. And the spheroidization mechanism of solid phase particles is as follows: α-Mg dendritic→dendritic arm coarsening→dendritic arm merging and irregular polygonization→spheroidization.

关 键 词：Mg-Gd-Zn-Zr合金 半固态 等温热处理 组织演变 

分 类 号：TG166.4[金属学及工艺—热处理]