Structural, electronic and elastic properties of AlFe2B2: First-principles study

The structural, electronic, and elastic properties of AlFe2B2 are investigated by first-principles calculations within the generalized gradient approximation. Our results reveal that AlFe2B2 is metallic and magnetic. The magnetic moments of the constituted elements are obtained and their origins are revealed. The computed elastic constants indicate that AlFe2B2 is mechanically stable but anisotropic, which is further confirmed by the shear anisotropic factor, direction-dependent bulk modulus and Young’s modulus. The calculated bulk modulus and shear modulus of AlFe2B2 are greater than these of FeAl, confirming the hardness-enhancement effect of boronizing. The calculated ratio B/G is 0.23 indicating that AlFe2B2 is brittle, and the obtained Poisson ratio is 0.23 implying that AlFe2B2 is a covalent–ionic crystal. These agree with the analyses performed on the partial density of states and Mulliken population. In addition, the velocities of acoustic waves are also computed, which ultimately gives a value of 764 K for the Debye temperature.