Effect of Alloying Elements on the Short-Range Orders and Atomic Diffusion Behavior of Liquid Al−9Si Cast Alloys

• Published in: Materials Vol. 16; no. 20; p. 6768
• Main Authors: Zhu, Xunming, Liu, Dan, Wang, Jian, Chen, Candong, Li, Xinxin, Wang, Li, Wang, Mingxu
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.10.2023; MDPI
• Subjects: AIMD; Alloying effects; Alloying elements; Alloys; Aluminum; Al−Si alloy; Atomic radius; Casting alloys; Communication; Copper; Copper base alloys; diffusion coefficient; Diffusion rate; Electronic structure; Enthalpy; Intermetallic compounds; Liquid alloys; liquid structure; Magnesium; Molecular dynamics; Short range order; Silicon; Simulation; Specialty metals industry; Tensile strength; Ternary alloys; Zinc
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma16206768

To investigate the influence of alloying elements (Zn, Mg, and Cu) on the structural and dynamical properties of liquid Al−9Si alloy, we conducted ab initio molecular dynamics (AIMD) simulations. Our results indicate that the structure of Al−Si−M ternary alloys is determined with a combination of atomic radii and mixing enthalpy, while the dynamic properties are primarily influenced by electronic structure of the alloying elements. Specifically, the addition of Cu promotes the formation of Al−Cu short-range order (SRO), while Zn has a higher propensity for Zn−Zn SRO. The Al−Cu SRO in liquid alloy may serve as the precursor for the Al2Cu reinforcing phase in Al−Si−Cu alloys. Upon the addition of Mg, a greater number of relatively stable perfect and distorted icosahedral structures, as well as hcp and bcc ordered structures with lower energies, are observed. Additionally, the presence of Mg leads to a reduction in the atomic diffusion rates of Al and Si, while Cu and Zn exhibit complex diffusion behavior influenced by the presence of Si atoms.