Influence of the electronic structure on the ductile behavior of B2 CsCl-type AB intermetallics

The study of the ductile B2, CsCl-type AB intermetallic compounds has been expanded over the past few years in order to determine the underlying principles that account for their ductility. Using a global semi-empirical alloy theory approach together with first-principles band theory, we show that absence of d-band electrons near the Fermi level accounts for the observed ductility in over 90% of the phases studied to date. This model has been used to predict the ductile/brittle behavior in several other selected AB compounds. Considering the crystal structures of the known intermetallics, it is concluded that the existence of these ductile AB B2 compounds is an isolated situation because the von Mises criterion for ductility is met in the B2 materials, but not in other crystal structures.