First-principles study on the electronic structure, bonding, stability of Mg/6H-SiC interfaces

Abstract

In order to investigate the atomic structure, electronic structure and stability of Mg/6H–SiC interfaces and explore the heterogeneous nucleation ability of SiC particles in Mg melt. The adhesion work, charge density difference and layer-projected density of states (LDOS) of Mg/6H–SiC interfaces are calculated by first-principles method. The results show that the adhesion work of C-terminated FCC structure is the largest among the six different interface structures. The interfacial electronic structures were analyzed by charge density difference, the total charge density of the C-terminated FCC interface is much greater than that of the Si-terminated HCP interface. The layer-projected DOS and Mulliken charge of the interface model reveal that the C-terminated interface is a mixed interface of polar covalent and ionic bonds, while the Si-terminated interface is mainly polar covalent bonds. The calculated interfacial energy of the Mg/6H–SiC interface is much larger than that between the α-Mg and magnesium melt, which proves that SiC particles cannot act as the nucleation sites of α-Mg.