Structural, Electronic and Elastic Properties of TMAl (TM=Co, Ni and Ru) Intermetallics: An ab-initio Study

Abstract

The structural, electronic, elastic, mechanical and thermal properties of transition metal aluminides (CoAl, NiAl and RuAl) have been investigated systematically using first principle density functional theory (DFT). Ground state properties such as lattice constant (a₀), bulk modulus (B) and its pressure derivative (B^?) are calculated which show well agreement with the experimental and other theoretical results. The electronic properties have been analyzed quantitatively. The values of elastic constants are also reported. The ductility of these compounds has been analyzed using the Pugh’s rule, Cauchy’s pressure (C₁₂-C₄₄) and electronic structure.  Our calculated results indicate that NiAl is ductile while CoAl and RuAl are brittle. The elastic properties such as Young's modulus (E), Poisson's ratio (?) and anisotropic ratio (A) are also reported. We have also correlated the ductility and bonding behaviour of these compounds.

Keywords: Density functional theory; intermetallic compounds; electronic properties; ductility; thermal properties.