First Principle Study of TiB₂ (0001)/γ-Fe (111) Interfacial Strength and Heterogeneous Nucleation

TiB₂/316L stainless steel composites were prepared by selective laser melting (SLM), and the adhesion work, interface energy and electronic structure of TiB₂/γ-Fe interface in TiB₂/316L stainless steel composites were investigated to explore the heterogeneous nucleation potential of γ-Fe grains on TiB₂ particles using first principles. Six interface models composed of three different stacking positions and two different terminations were established. The B-terminated-top 2 site interface ("B-top 2") was the most stable because of the largest adhesion work, smallest interfacial distances, and smallest interfacial energy. The difference charge density and partial density of states indicated that a large number of strong Fe-B covalent bonds were formed near the "B-top 2" interface, which increased the stability of interface. Fracture analysis revealed that the bonding strength of the "B-top 2" interface was higher than that of the Fe matrix, and it was difficult to fracture at the interface. The interface energy at the Ti-poor position in the "B-top 2" interface model was smaller than that of the γ-Fe/Fe melt, indicating that TiB₂ had strong heterogeneous nucleation potency for γ-Fe.