Research on First-principles of Strengthening Effects of Y and Mg3Zn3Y2 on Mg Alloys
The effect of adding Y element on the mechanical properties of Mg-Zn-Zr alloy was studied using first-princi-ples,the effect of the second phase compound Mg3Zn3Y2 on the mechanical properties of Mg-Zn-Zr-Y alloy was studied with a Y/Zn molar ratio of 0.5.The research results showed that the stress of Mg-Zn-Zr and Mg-Zn-Zr-Y alloys reaches its maximum at strains around 0.19 and 0.21 respectively.The ideal tensile strength of Mg-Zn-Zr-Y alloy was significantly higher than that of Mg-Zn-Zr alloy.The analysis results of density of states and differential charge density showed that Mg-Y bonds have strong covalence,which leaded to an improvement on the ideal tensile strength of Mg-Zn-Zr-Y alloy.The cal-culated Young's modulus E of Mg3Zn3Y2 was 70.26 GPa and Poisson's ratio v was at 0.261,the Cauchy pressure C12-C44＜0 indicated that Mg3Zn3Y2 was brittle and increased the stiffness of Mg-Zn-Zr-Y alloy.
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