First-Principles Study on Graphene/Mg 2 Si Interface of Selective Laser Melting Graphene/Aluminum Matrix Composites.

The bonding strength of a Gr/Mg₂Si interface was calculated by first principles. Graphene can form a stable, completely coherent interface with Mg₂Si. When the (0001) _Gr/(001) _Mg2Si crystal plane is combined, the mismatch degree is 5.394%, which conforms to the two-dimensional lattice mismatch theory. At the interface between Gr/Mg₂Si, chemical bonds were not formed, there was only a strong van der Waals force; the interfaces composed of three low index surfaces (001), (011) and (111) of Mg₂Si and Gr (0001) have smaller interfacial adhesion work and larger interfacial energy, the interfacial energy of Gr/Mg₂Si is much larger than that of α-Al/Al melt and Gr/Al interfacial (0.15 J/m², 0.16 J/m²), and the interface distance of a stable interface is larger than the bond length of a chemical bond. The interface charge density difference diagram and density of states curve show that there is only strong van der Waals force in a Gr/Mg₂Si interface. Therefore, when the Gr/AlSi10Mg composite is stressed and deformed, the Gr/Mg₂Si interface in the composite is easy to separate and become the crack propagation source. The Gr/Mg₂Si interface should be avoided in the preparation of Gr/AlSi10Mg composite. [ABSTRACT FROM AUTHOR]