Solute-homogenization model and its experimental verification in Mg-Gd-based alloys. Issue 7 (July 2018)

• Record Type: Journal Article
• Authors: Qian, Shengnan; Dong, Chuang; Liu, Tianyu; Qin, Ying; Wang, Qing; Wu, Yujuan; Gu, Lidong; Zou, Jianxin; Heng, Xiangwen; Peng, Liming; Zeng, Xiaoqin
• Is Part Of: Journal of materials science & technology. Volume 34:Issue 7(2018)
• Page Start: 1132
• Page End: 1141
• Publication Date: 2018-07
• Subjects: Mg-Gd solid solution -- Cluster-plus-glue-atom model -- Solute-homogenization model -- Mg-Gd-Y-Zr cast alloys; Metals -- Periodicals; Materials science -- Periodicals; Materials science; Metals; Periodicals; 620.1105
• DOI: 10.1016/j.jmst.2017.11.053
• Languages: English
• ISSNs: 1005-0302

Abstract

Abstract: Composition homogenization in solid solution is important for industrial alloys. In the present work, a solute homogenization model is proposed based on the chemical short-range-order tendency in Mg-Gd-based alloys. After a calculation using the cluster-plus-glue-atom model, the stable Mg-Gd structural unit is derived, [Gd-Mg12 ]Mg6, where one solute Gd is nearest-neighbored with twelve Mg atoms to form the characteristic hcp cluster [Gd-Mg12 ] and this cluster is matched with six Mg glue atoms. Such a local unit is then mixed with [Mg-Mg12 ]Mg3, the stable unit for pure Mg. Assuming that the Gd-containing units are arranged in fcc- or bcc-like lattice points and the Mg units in their octahedral interstices, three proportions between the two units are obtained, 1:1, 2:3, and 1:3, which constitute three solute homogenization modes. The prevailing Mg-Gd-based alloys are consequently classified into three groups, respectively exemplified by GW103 K (Mg-10Gd-3Y-0.4Zr, wt%), GW83 K (Mg-8Gd-3Y-0.4Zr), and GW63 K (Mg-6Gd-3Y-0.4Zr). Mg-Gd-Y-Zr alloys were designed following the model (where Y and Zr were also added in substitution for Gd) and prepared by permanent-mould casting. According to their mechanical properties, the 1:3 alloy (Mg-5.9Gd-1.6Y-0.4Zr) shows the best comprehensive properties (ultimate tensile strength 305 MPa, yield strength 186 MPa, elongation 9.0%) in solution plus ageing state.