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

• 来源期刊: 材料科学技术（英文版）
• 年，卷（期）: 2019,（9）
• 页码范围: 2058-2063
• 页数: 6页
• 语种: 英文

摘要

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 (A),b =9.4886 (A),and c =8.5966 (A).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.