First-principles study of Y, Ca microalloyed Mg-Zn alloy

• Published in: Materials today communications 2024-12, Vol.41, p.110936, Article 110936
• Main Authors: Jin, Shuaishuai, You, Zhiyong, Han, Peide, Jiang, Aoxue, Sun, Chunle, Han, JiaMin, Song, ZhenYang, Li, Bing
• Format: Article
• Language: English
• Subjects: Alloying; Elastic constants; Electronic structure; G.P. zones
• ISSN: 2352-4928; 2352-4928
• DOI: 10.1016/j.mtcomm.2024.110936

This article investigates the complex effects of Y and Ca alloying on the G.P. zones ( parallel to {0001}Mg)and G.P.1 zones ( parallel to {2−1−10}Mg) in Mg-Zn alloys, as well as their corresponding changes in thermal stability, electronic structure, and mechanical properties, using first-principles calculations. The addition of Y significantly enhances the thermal stability of both the G.P. and G.P.1 zones, whereas the effect of Ca is more limited, mainly enhancing the thermal stability of the one-atomic layer G.P. zones, but possibly decreasing the thermal stability in other areas. In the combined alloying of Y and Ca, the cooperative effect optimizes the thermal stability of the one-atomic layer and half-atomic layer G.P.1 zones, but reduces the thermal stability of other G.P. zones. Through studying the local density of states and the atomic radial distribution function, it is revealed that the higher stability of the half-atomic layer G.P. zones compared to the one-atomic layer G.P. zones is due to more Mg-Zn and Mg-Mg bonds, whereas the one-atomic layer G.P.1 zones exhibits higher stability because of shorter and more stable Zn-Zn, Mg-Zn, and Zn-Mg bonds. The electronic structure analysis shows that Y mainly appears in the alloy in the form of electron localization, readily forming ionic bonds with Mg and Zn, which is a key reason for its effective alloying results. In contrast, Ca, as well as the alloying of Y and Ca, do not form effective bonds on the energy levels from −8 eV to −5 eV, explaining their weaker alloying effects. Additionally, the study of mechanical properties indicates that the G.P. zones of pure Zn, due to its significant difference in shear modulus from the magnesium matrix, is not easily strengthened by dislocation shearing and thus mainly strengthened through the Orowan mechanism. The addition of Y significantly increases the strength and hardness of the one-atomic layer G.P. zones, but decreases the ductility. The addition of Ca changes the anisotropy of the Young's modulus of the one-atomic layer G.P. zones, while the combined effect of Y and Ca greatly alters the anisotropy of the shear modulus of this phase. These findings provide important theoretical guidance and insights for the design and application of Mg-Zn alloys. [Display omitted]