The structures with different compositions of the binary Mg–Y alloys have been predicted by first-principles calculations combined with an unbiased Crystal structure Analysis by Particle Swarm Optimization (CALYPSO) structure searching method. The two already known stoichiometries alloys of Mg1Y1 with Pm-[Formula: see text] symmetry and Mg3Y1 with Fm-[Formula: see text] are confirmed, and a new stoichiometry alloy of Mg1Y3 with [Formula: see text] symmetry is proposed. The dynamical and mechanical stabilities for the three alloys at different pressures are investigated by phonon spectra and mechanical stability criteria, respectively. Subsequently, the bulk modulus, shear modulus, Young’s modulus, the brittleness/ductile behavior, the elastic anisotropy as well as Vickers hardness for the three alloys at 0 GPa are discussed in detail. The results show that the Mg1Y1, Mg3Y1 and Mg1Y3 alloys improve the hardness and stiffness compared with pure Mg, and Mg1Y3 alloy is of the best ductility in the three alloys. Meanwhile, the three alloys exhibit anisotropic. Moreover, the thermodynamic properties, such as Debye temperature, heat capacity at constant volume, entropy and Helmholtz free energy for the three stable alloys, are predicted and discussed.

中文翻译：

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基于第一性原理计算的 Mg-Y 合金的结构、力学和热力学性能研究

通过第一性原理计算结合粒子群优化（CALYPSO）结构搜索方法的无偏晶体结构分析，预测了二元Mg-Y合金不同成分的结构。镁的两种已知化学计量合金1是1具有 Pm-[公式：见正文] 对称性和 Mg3是1与 Fm-[公式：见正文] 得到确认，并且一种新的化学计量合金 Mg1是3提出了[公式：见正文]对称性。分别通过声子光谱和机械稳定性标准研究了三种合金在不同压力下的动态和机械稳定性。随后，详细讨论了三种合金在0 GPa时的体积模量、剪切模量、杨氏模量、脆性/延性行为、弹性各向异性以及维氏硬度。结果表明，Mg1是1, 镁3是1和镁1是3与纯镁相比，合金提高了硬度和刚度，而镁1是3合金是三种合金中延展性最好的。同时，这三种合金表现出各向异性。此外，预测和讨论了三种稳定合金的德拜温度、定容比热容、熵和亥姆霍兹自由能等热力学性质。