Electrical conductive and damage-tolerant nanolaminated MAB phases Cr2AlB2, Cr3AlB4 and Cr4AlB6

Abstract

Theoretical investigations on electronic structure, chemical bonding and mechanical properties reveal that MAB phases (CrB2)nCrAl (n = 1–3) exhibit anisotropic electrical and elastic properties, low shear deformation resistance and damage tolerance similar to MAX phases. The main contribution to the electrical conductivity is Cr 3d states and the anisotropic distribution of Cr atoms results in anisotropic conductivity. The high stiffness originates from the strong covalent B–B bonds, while the low shear deformation resistance is underpinned by metallic B–Cr bonds adjacent to Al layer. The possible slip systems are (100)[010], (010)[100], (010)[001] and (001)[010] for Cr2AlB2, (010)[001] and (001)[010] for Cr3AlB4 and Cr4AlB6.