First-principles calculations of the β'-Mg_7Gd precipitate in Mg-Gd binary alloys

• 来源期刊: 科学通报(英文版)
• 学科: 物理学
• 年，卷（期）: 2011,（11）
• 页码范围: 1142-1146
• 页数: 5页
• 分类号: O481
• 语种: 中文

摘要

The metastable β' phase is often the most effective hardening precipitate in Mg-Gd based alloys.In this paper,the structural,elastic and electronic properties of the recently identified β'-Mg7Gd precipitate in Mg-Gd binary alloys were investigated using first-principles calculations based on density functional theory.The lattice mismatches between the coherent β'-Mg7Gd precipitate and α-Mg matrix are discussed and used to rationalize the experimentally observed morphology of the precipitate.The mechanical properties were investigated through analysis of the single-crystal elastic constants and the polycrystalline elastic moduli.It is found that β'-Mg7Gd is brittle in nature.Strong covalent bonding in β'-Mg7Gd,as inferred from its electronic structure,further explains its mechanical properties.Our theoretical results show good agreement with experimental measurements.