Density functional theory study of Al/NbB2 heterogeneous nucleation interface

Abstract

By using density functional theory based on the first-principles method, the interfacial adhesion, stability and bonding nature of Al(1 1 1)/NbB2 (0 0 0 1) were studied to investigate the heterogeneous nucleation potential of α-Al grains on NbB2 particles. For Al(1 1 1)/NbB2 (0 0 0 1) interface, there are six different models that are Nb-terminated and B-terminated interfaces with different stacking sequences (top-site, hollow-site, and bridge-site), respectively. The research show that B-terminated-hollow-sited interface with the largest work of adhesion and smallest interfacial energy is the most stable and preferred among six different models, and interfacial energy of the model is lower than that of α-Al/Al melt, 0.15 J/m2. Furthermore, the difference charge density and partial density of states are presented to discuss bonding nature of the interface. B-terminated-hollow-sited interface have more covalent features than that of the others. For Nb-terminated-hollow-sited interface, Nb–Al metallic bonds are formed across interface. As a result, α-Al grains is inclined to form nucleus on the B-terminated-hollow-sited NbB2 (0 0 0 1).