Structures, elastic, electronic properties and phase stability of Ni–Sc intermetallic compounds from first-principles investigation

Abstract

First-principles method based on density functional theory has been performed to study the lattice structures, elastic properties, Debye temperatures, electronic properties and phase stability of Ni–Sc intermetallic compounds systematically. The calculated lattice parameters are close to available experimental data. The analysis results of formation enthalpies indicate that the Ni–Sc compounds are all thermodynamically stable and NiSc is the most stable. Besides, these compounds are also mechanically stable according to the mechanical stability criterion. The obtained shear modulus G and Young’s modulus E show that Ni5Sc is the stiffest and the most covalent compound. The discussion about G/B (the ratio of shear modulus to bulk modulous), Poisson’s ratio [Formula: see text] and Cauchy pressure demonstrate that all Ni–Sc compounds are ductile and NiSc2 is the most ductile phase, followed by NiSc. The results of Debye temperatures indicate that Ni5Sc has the stronger covalent bonds than others. Finally, the electronic properties are investigated to reveal the underlying mechanical properties.