第一性原理研究Mg(16-x)Tix(x=1-16)合金的晶体结构和力学性质

First-principles studies of crystal structure and mechanical properties of Mg(16-x)Tix(x=1-16) alloys

摘要:

设计力学性能良好的新型镁钛合金对于促进汽车工业、固态储氢材料以及生物复合材料具有重要的意义. 本文基于第一性原理计算, 以能量为判据, 筛选出了Mg(16-x)Tix(x=1~16)每个组分下最稳定的晶体结构, 同时通过形成能、声子谱以及弹性常数对相对稳定的Mg15Ti1, Mg2Ti2, Mg1Ti15晶体结构进行了详细的研究. 研究结果表明镁钛合金是不相溶的, 形成的结构均为亚稳态结构且是热力学稳定的, 此外钛含量的增加有利于增加镁钛合金的硬度以及延展性, 这与实验结果一致, 但是会降低共价键的强度.

Abstract:

The design of new magnesium titanium alloy with good mechanical properties is of great significance for promoting automobile industry and solid hydrogen storage materials as well as biocomposite. In this article, the most stable crystal structure of each component in Mg(16-x)Tix(x=1~16) is selected using energy as criterion based on first principle calculation. At the same time, the structure of relatively stable Mg15Ti1, Mg2Ti2, Mg1Ti15 was studied using physical quantities such as forming energy, phonon spectrum and elastic constant. The results show that the magnesium-titanium alloy is incompatible, and forms thermodynamic stable metastable structure. The increase in titanium content is beneficial to increase the hardness and ductility of the magnesium-titanium alloy, which is consistent with experimental results, but it reduces the strength of the covalent bond.