Elastic constants of AlB2-type compounds from first-principles calculations

Abstract Elastic constants ( C ij ’s) of 24 compounds in the AlB 2 -type diborides have been calculated by first-principles with the generalized gradient approximation and compared with the available experimental data. Values of all independent elastic constants as well as bulk modulus in a and c directions ( B a and B c , respectively) were predicted. The elastic modulus of the AlB 2 -type compounds were calculated according to the theoretical elastic constants by Voigt–Reuss–Hill averaging scheme. Ductility and anisotropy in these compounds were further analyzed based on their B / G ratio and elastic constants. It is founded that AlB 2 is more ductile while ScB 2 is more brittle, and AlB 2 has a highest elastic anisotropy in the 24 AlB 2 -type compounds.