Microalloying for ductility in molybdenum disilicide

Abstract

The effects of substitutional alloying on the ductility of MoSi₂ single crystals are studied. Criteria for ductility and brittleness are expressed in terms of surface energies and generalized stacking fault energy surfaces, which are calculated using first principles density functional methods. The results are expressed in terms of a single disembrittlement parameter, based on fracture mechanics theory, which characterizes brittle versus ductile behavior. Substitution of Mo by V, Nb, Tc and Re and substitution of Si by Mg, Al, Ge and P were considered. The effects of substitution of Mo by V or Nb, and substitution of Si by Mg or Al are found to be particularly beneficial to the enhancement of ductility.