The effects of boron and sulfur impurities on the ideal cleavage fracture properties of ${\mathrm{Ni}}_3$Al under tensile stress are investigated using the full-potential linear-muffin-tin-orbital total-energy method, with a repeated slab arrangement of atoms simulating an isolated cleavage plane. Results for the stress-strain relationship, ideal cleavage energies, ideal yield stress and strains with and without impurities are presented, and the electronic mechanism underlying the contrasting effects of boron and sulfur impurities on the ideal cleavage of ${\mathrm{Ni}}_3$Al is elucidated. © 1996 The American Physical Society.

• Received 21 November 1995

DOI:https://doi.org/10.1103/PhysRevB.54.3074