Elastic and brittle properties of the B2-MgRE (RE = Sc, Y, Ce, Pr, Nd, Gd, Tb, Dy, Ho, Er) intermetallics
Department of Applied Physics, Hunan University, Changsha 410082, China, and Materials Science and Engineering College, Hunan University, Changsha, 410082, P.R. China
Corresponding author: a email@example.com
Revised: 25 October 2007
Published online: 29 November 2007
The brittle and elastic properties of the B2-MgRE (RE = Sc, Y, Ce, Pr, Nd, Gd, Tb, Dy, Ho, Er) intermetallics have been investigated using first-principles density functional calculations. The calculated equilibrium lattice constants and enthalpies of formation are in overall agreement with the available experiment and theoretical results. The related physical properties of those compounds are compared with that of ductile YCu. The Fermi energy occurs above a peak in the DOS for B2-MgRE intermetallics, whereas for ductile YCu the Fermi energy occurs near a minimum in the DOS. For B2-YCu, the partial density of states of d-states at the Fermi energy is low, while for B2-MgRE the RE d-states are partially occupied, indicating their important roles in the directional bonding for this material. The Cauchy pressure (C12-C44) and the ratio of bulk to shear modulus B/G are used to assess the brittle/ductile behavior of B2-MgRE and YCu compounds. It can be concluded that the B2-MgRE alloys have brittle behavior. MgSc is the most brittle, and MgHo is the least brittle amongst those alloys.
PACS: 71.15.Mb – Density functional theory, local density approximation, gradient and other corrections / 71.20.Lp – Intermetallic compounds / 62.20.Dc – Elasticity, elastic constants
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2007