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

doi:10.13251/j.issn.0254-6051.2020.02.033

Abstract

Abstract:

Semi-solid spheroidized microstructure was obtained by isothermal treatment on as-cast Mg-15Gd-2Zn-0.6Zr 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.

Key words: Mg-Gd-Zn-Zr alloy, semi-solid, isothermal heat treatment, microstructure evolution

CLC Number:

TG166.4

Yin Jian, Lu Chunhui, Xie Shikun, Yi Rongxi, Huang Wenxian. Effect of isothermal heat treatment on semi-solid microstructure of Mg-Gd-Zn-Zr alloy[J]. HTM, 2020, 45(2): 175-180.

References

[1]谢水生, 李兴刚. 半固态加工技术在镁合金零部件生产中的应用[J]. 世界有色金属, 2005(2): 39-48.
Xie Shuisheng, Li Xinggang. Application of semi-solid processing technology in the production of magnesium alloy parts[J]. World Nonferrous Metals, 2005(2): 39-48.
[2]李春, 董晓刚, 袁训锋, 等. 半固态ZA96镁合金部分重熔过程中的组织演变[J]. 特种铸造及有色合金, 2015, 35(3): 268-271.
Li Chun, Dong Xiaogang, Yuan Xunfeng, et al. Microstructure evolution of semi-solid ZA96 magnesium alloy during partial remelting process[J]. Special Casting & Nonferrous Alloys, 2015, 35(3): 268-271.
[3]范俊凯, 杨光昱, 陶慧勇, 等. Mg-5.5Zn-2Gd-0.6Zr合金的简化SIMA法等温半固态组织粗化规律[J]. 稀有金属材料与工程, 2015, 44(9): 2196-2202.
Fan Junkai, Yang Guangyu, Tao Huiyong, et al. Isothermal grain coarsening of extruded Mg-5.5Zn-2Gd-0.6Zr magnesium alloy by simple strain-induced melt activation process[J]. Rare Metal Materials and Engineering, 2015, 44(9): 2196-2202.
[4]邵俊, 闫洪, 黄文先, 等. Y对AZ91镁合金半固态等温热处理组织的影响[J]. 稀土, 2014, 35(4): 47-51.
Shao Jun, Yan Hong, Huang Wenxian, et al. Effect of Y on microstructure of semi-solid isothermal heat-treated AZ91 magnesium alloy[J]. Chinese Rare Earths, 2014, 35(4): 47-51.
[5]Jiang J F, Lin X, Wang Y, et al. Microstructural evolution of AZ61 magnesium alloy predeformed by ECAE during semisolid isothermal treatment[J]. Transactions of Nonferrous Metals Society of China, 2012, 22(3): 555-563.
[6]Zhang L, Wu G, Cao Z, et al. Effects of Ca content on the microstructure of semisolid Mg-13Al alloy produced via isothermal heat treatment[J]. Journal of Alloys & Compounds, 2012, 534(17): 52-58.
[7]Zhang Liang, Cao Zhanyi, Liu Yongbing. Microstructure evolution of semi-solid Mg-14Al-0. 5Mn alloys during isothermal heat treatment[J]. Transactions of Nonferrous Metals Society of China, 2010, 20(7): 1244-1248.
[8]孙兵, 张英波, 权高峰, 等. AZ80镁合金半固态等温处理过程中的组织演变[J]. 稀有金属材料与工程, 2016, 45(2): 404-408.
Sun Bing, Zhang Yingbo, Quan Gaofeng, et al. Microstructures evolution of AZ80 magnesium alloy in semi-solid isothermal treatment process[J]. Rare Metal Materials and Engineering, 2016, 45(2): 404-408.
[9]胡勇, 饶丽, 黎秋萍, 等. 等温热处理对AZ91D+Ce镁合金半固态组织的影响[J]. 稀有金属材料与工程, 2016, 45(2): 493-497.
Hu Yong, Rao Li, Li Qiuping, et al. Effect of isothermal heat treatment on the microstructure of semi-solid AZ91D+Ce magnesium alloy[J]. Rare Metal Materials and Engineering, 2016, 45(2): 493-497.
[10]黄晓锋, 马亚杰, 张玉, 等. 等温热处理对ZC61-0.3Cr镁合金半固态组织演变的影响[J]. 中国有色金属学报, 2018, 28(10): 1962-1971.
Huang Xiaofeng, Ma Yajie, Zhang Yu, et al. Effects of isothermal heat treatment on microstructural evolution ZC61-0.3Cr magnesium alloy[J]. The Chinese Journal of Nonferrous Metals, 2018, 28(10): 1962-1971.
[11]刘晓波, 杨淼, 赵宇光, 等. 等温时间对半固态挤压Mg₂Si/Al复合材料组织和力学性能的影响[J]. 金属热处理, 2019, 44(8): 158-165.
Liu Xiaobo, Yang Miao, Zhao Yuguang, et al. Effect of isothermal time on microstructure and mechanical properties of semi-solid extruded Mg₂Si/Al composites[J]. Heat Treatment of Metals, 2019, 44(8): 158-165.
[12]龚文源, 张贵杰, 郑小平, 等. 半固态AZ91D镁合金坯料热压缩后的显微组织[J]. 金属热处理, 2017, 42(8): 36-39.
Gong Wenyuan, Zhang Guijie, Zheng Xiaoping, et al. Microstructure of semi-solid AZ91D magnesium alloy after hot compression[J]. Heat Treatment of Metals, 2017, 42(8): 36-39.

[13]Gao Lei, Liang Songmao, Chen Rongshi, et al. Microstructure evolution during reheating of extruded Mg-Gd-Y-Zr alloy into semisolid state[J]. Transactions of Nonferrous Metals Society of China, 2010, 20(9): 1585-1590.
[14]李志涛, 李全安, 陈晓亚. Gd对铸态Mg-4Y-2Sm-0.5Zr合金组织与性能的影响[J]. 金属热处理, 2019, 44(6): 69-74.
Li Zhitao, Li Quanan, Chen Xiaoya. Effect of Gd on microstructure and properties of as-cast Mg-4Y-2Sm-0.5Zr alloy[J]. Heat Treatment of Metals, 2019, 44(6): 69-74.
[15]胡传凯, 赵强, 王艳彬, 等. Mg-10Gd-3Y-Zr镁合金的热处理工艺[J]. 金属热处理, 2018, 43(9): 94-97.
Hu Chuankai, Zhao Qiang, Wang Yanbin, et al. Heat treatment of Mg-10Gd-3Y-Zr magnesium alloy[J]. Heat Treatment of Metals, 2018, 43(9): 94-97.
[16]Meng Yi, Chen Qiang, Sumio Sugiyama, et al. Effects of reheating and subsequent rapid cooling on microstructural evolution and semisolid forming behaviors of extruded Mg-8.20Gd-4.48Y-3.34Zn-0.36Zr alloy[J]. Journal of Materials Processing Technology, 2017, 247: 192-203.
[17]Li Juncai, He Zongling, Fu Penghuai, et al. Heat treatment and mechanical properties of a high-strength cast Mg-Gd-Zn alloy[J]. Materials Science & Engineering A, 2016, 651: 745-752.
[18]Voorhees P W. The theory of Ostwald ripening[J]. Journal of Statistical Physics, 1985, 38(1/2): 231-252.
[19]毛卫民. 半固态金属成形技术[M]. 北京: 机械工业出版社, 2004: 277.
[20]管仁国, 马伟民. 金属半固态成形理论与技术[M]. 北京: 冶金工业出版社, 2005: 273.
Guan Renguo, Ma Weimin. Semi-solid Forming Theory and Technology of Metals[M]. Beijing: Metallurgical Industry Press, 2005: 273.
[21]曾小勤, 吴玉娟, 彭立明, 等. Mg-Gd-Zn-Zr合金中的 LPSO 结构和时效相[J]. 金属学报, 2010, 46(9): 1041-1046.
Zeng Xiaoqing, Wu Yujuan, Peng Liming, et al. LPSO structure and aging phases in Mg-Gd-Zn-Zr alloy[J]. Acta Metallurgical Sinica, 2010, 46(9): 1041-1046.