Study on the synergistic effect of Y and Nd to significantly improve the corrosion resistance of Mg-Zn-Gd series alloy

Abstract

In this study, the synergistic effect of Y and Nd on the microstructure and corrosion resistance of Mg-1.8Zn-1.2Gd-0.5Zr-0.3Ca (wt%) alloys was investigated. The results show that the addition of Nd refines the grain but deteriorates the corrosion resistance, which is primarily attributed to the formation of a more inhomogeneous second phase (Mg₄₁Nd₅) exhibiting a significant potential difference with the matrix and leading to galvanic coupling corrosion. With Y addition, the corrosion resistance of the alloy is progressively enhanced, because Y promotes the formation of the 14H-LPSO phase, which is favorable for enhancing the corrosion resistance. First-principles calculations reveal that the addition of Y can effectively inhibit the diffusion of Nd in the magnesium alloy matrix, thereby improving corrosion resistance.