J. Mater. Sci. Technol. ›› 2019, Vol. 35 ›› Issue (9): 2058-2063.DOI: 10.1016/j.jmst.2019.05.013

• Orginal Article • Previous Articles     Next Articles

Atomic structure and enhanced thermostability of a new structure MgYZn4 formed by ordered substitution of Y for Mg in MgZn2 in a Mg-Zn-Y alloy

Lifeng Zhanga, Shangyi Maa, Weizhen Wangba, Zhiqing Yanga*(), Hengqiang Yea   

  1. a Shenyang National laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, School of Materials Science and Engineering, University of Science and Technology of China, Shenyang, 110016, China
    b School of Materials Science and Engineering, Northeastern University, Shenyang, 110819, China
  • Received:2018-09-18 Revised:2018-11-05 Accepted:2018-11-05 Online:2019-09-20 Published:2019-07-26
  • Contact: Yang Zhiqing
  • About author:

    1 These authors contributed equally to this work.

Abstract:

A new phase MgYZn4 in Mg-Zn-Y alloy was studied using aberration-corrected scanning-transmission electron microscopy and first-principles calculations. Nanometer-sized MgYZn4 precipitates were formed through ordered substitutions of Y with 50% Mg atoms in MgZn2. MgYZn4 has an orthorhombic structure with a space group of Pmnn, and lattice parameters a =5.2965 ?, b =9.4886 ?, and c =8.5966 ?. Importantly, both size and structure of MgYZn4 are stable at 625 K for 5 h, showing higher thermostability than MgZn2, which should be important for applications at elevated temperatures. The enhanced thermostability of MgYZn4 is attributed to the lower formation energy and bonding enhancement due to Y substitution.

Key words: MgYZn4, Thermostability, Laves phase, Precipitate, Mg alloys