Effects of Point Defects on Properties of B2 NiAl: A First-principles Study

The basic properties, heats of formation, energies of formation, equilibrium concentration of point defects, elastic properties, and electronic structures for point defect structures of B2-NiAl crystal were analyzed by the density functional theory. Compared with B2-NiAl and other B2 intermetallic compounds, purity NiAl has better ductility and bonding strength. According to the calculated heats of formation, energies of formation, and equilibrium concentration of point defects, the Ni antisite and Ni vacancy are primary defects in B2-NiAl crystal. The calculated G/B₀ and Cauchy pressure parameters C₁₂-C₄₄ values confirm that Ni vacancy, Ni antisite, and Al antisite can promote the brittleness of B2-NiAl, in which Ni vacancy is the primary defect, while Al vacancy with a low concentration can improve ductility of B2-NiAl. The density of state confirms that B2-NiAl intermetallic compounds are conductors, and point defects can promote the stability of the system expect Ni antisite defect.