First-principles study of typical precipitates in creep resistant magnesium alloys

First-principles calculations were performed to study the mechanical properties of typical precipitates of creep resistant magnesium alloys (Mg2Si, Mg2Ge, Mg2Sn and Mg3Zn3Y2). Formation enthalpies and cohesive energies, elastic constants C11, C12, C44, bulk modulus B0, Young's modulus E, shear modulus G, the ratios of shear modulus to bulk modulus G/B0, negative Cauchy pressure parameter (C12-C44) and Poisson's ratio ν of four precipitates were discussed. The results show that Mg2Si and Mg2Ge are stiffer than Mg3Zn3Y2. The charge density was further investigated to clarify the electronic causes.