First-principles calculations on electronic structure and interfacial stability of Mg/NbB2 heterogeneous nucleation interface

Abstract

ABSTRACT The atomic structure, electronic property, work of adhesion and interface energy of the interface between α-Mg and NbB2 were studied by the first-principles calculations to investigate the heterogeneous nucleation potential of NbB2 particles as nucleation substrate for α-Mg grains. The convergence test shows that the NbB2 (0001) slabs with 9 atomic layers exhibit bulk-like interior feature. The stacking sequences of Mg atoms onto the surface of NbB2 (0001) slabs were analyzed. It was found that the “HCP” stacking sequence was most stable due to the maximum bonding work and minimum interfacial distance. The results of differential charge density and partial density of states (PDOS) study indicate that the B-terminated interface contains strong covalent/weak metal bonds, and the Nb-terminated interface exist strong metal bond characteristics. The calculation results of Mg/NbB2 interface energy elucidating that NbB2 particles can act as effective nucleation substrate on α-Mg grains to refine α-Mg grains under certain conditions.