Theoretical study of active Ca element on grain refining of carbon-inoculated Mg-Al alloy

• Published in: Materials & design 2020-07, Vol.192, p.108664, Article 108664
• Main Authors: Yang, Shu-Qing, Li, Cheng-Bo, Du, Jun, Zhao, Yu-Jun
• Format: Article
• Language: English
• Subjects: Critical nucleation radius; First-principles calculation; Heterogeneous nucleation; Interfacial properties; Mg-Al alloy
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2020.108664

It is crucial to study grain refinement and refinement mechanism for promoting mechanical properties of Mg alloys. In this work, the influence mechanism of Ca on the grain refinement of Al2MgC2 and Al4C3 in Mg alloys was studied. It shows that Ca is easier to adsorb on the surfaces of Al2MgC2 and Al4C3 particles than Mg, which further promotes the adsorption Mg on the surfaces of Al2MgC2 and Al4C3 particles, leading to more crystal nuclei beyond the critical nucleation radius rK. The interface of Ca replaced Mg-2 is found to be more stable, for both Mg/Al2MgC2 interface and Mg/Al4C3 interface. We further revealed that Ca could effectively migrate from the first-layer to the second-layer in both the adsorption slabs and doped interface slabs under ambient condition. Ca is easier to adsorb on Al2MgC2 and Al4C3 surfaces, and then promote the subsequent adsorption of Mg. For the Al2MgC2 and Al4C3 particles with radius (rK1) slightly smaller than the critical nucleation radius rK, there are chances that their size beyond rK after the adsorption, and thus enhancing the nucleation rate. [Display omitted] •Al2MgC2 and Al4C3 particles are more easily to adsorb around molten Mg due to the adsorption of Ca.•The doping of Ca makes Mg/Al2MgC2 and Mg/Al4C3 interfaces more stable.•Ca could effectively migrate from first-layer to the second-layer in the initial nucleating stage.•The size of Al2MgC2 and Al4C3 particles.