Effect of Adding Third Element on Deformability of Mg–Al Alloy

In recent years, magnesium is expected to be used as a structural material in vehicles. Since limited slip systems in magnesium induces marked yield anisotropy and poor deformability at room temperature, there is a specific demand for developing magnesium alloys with reduced plastic anisotropy. In this study, we focused on the Mg–Al system alloy, which is widely used in commerce, and examined the third element contributing to the reduction of the plastic anisotropy. Generalized stacking fault energy (GSFE), which corresponds to the energy for sliding atomic layer along a slip plane, was calculated in the first-principles calculations to estimate deformability of ternary Mg–Al-X alloys adding the third element X, to the Mg–Al binary alloy. As the third element X, Zn, Zr, and Gd were selected. The slip properties were evaluated using the unstable stacking fault energy (USFE), which represents the maximum value of GSFE. The result suggested that the addition of zirconium contributes most to the reduction of plastic anisotropy.