Promoting wetting of Mg on the SiC surfaces by addition of Al, Zn and Zr elements: A study via first-principle calculations

Abstract

When preparing SiC/Mg composites, alloy elements play key roles in the nucleation and interfacial wetting. In this paper, effects of Al, Zn and Zr additions on the Mg/SiC interfacial bonding properties were investigated comprehensively via method of first-principle calculations. Mg(0001)/SiC(0001) interfaces with different terminations and stacking sequences were built and C Ⅱ-T C Ⅱ top interface has the largest work of adhesion (Wad). Zn dopants can not improve the Wad for both C-T and Si-T interfaces. Al atom can only strengthen the C-T interface. Zr addition can greatly improve the Wad for both C-T and Si-T interfaces. Wad of C-T interfaces can reach up to 11.55 J/m2 and 12.55 J/m2 after doping 1 monolayer (ML) of Al and Zr atoms. Larger Wad can lead to lower contact angles of Mg on SiC surfaces, which can improve wetting and nucleation in SiC/Mg composites. Analysis of electronic structure shows that Al-C and Zr-C bonds have more covalent composition than the Mg-C bond, which is responsible for the improvement of interfacial bonding strength. Experimental results in references were also analyzed, which are in well agreement with our calculation results.