Mechanical and electronic properties of 5d transition metal diborides M B2 (M=Re, W, Os, Ru)

Abstract

First-principles method is used to investigate the structural, mechanical, and electronic properties of 5d transition metal diborides M B2 (M=Re, W, Os, Ru). Our calculations show hexagonal ReB2 and WB 2 have much larger elastic moduli and tensile shear strengths than orthorhombic OsB2 and RuB2. The elastic moduli and ideal strength are both calculated to be in a sequence of ReB2 > WB 2 > OsB2 > RuB2. Electronic structures show that strong directional covalent B-B and M-B bonds exist in the materials, which is the origin of their high modulus, large strength, and high hardness. © 2009 American Institute of Physics.