On the contribution of climb to high-temperature deformation in single phase γ-TiAl

Abstract

This study has assessed the contribution of climb to the plastic deformation of TiAl when deformed at elevated temperatures where significant ductility is realized. It is shown that the motion of dislocations with Burgers vectors, b, given by b = 1/2〈110] is achieved by either or both glide and climb, the degree to which these various mechanisms contribute depending on temperature and strain rate. Thus, at 900°C and strain rates less than approximately 10⁻²s⁻¹, climb is found to contribute rather significantly to plastic deformation. A model is proposed which involves both glide and climb; initially, the deformation substructure is developed by glide until the appropriate link length for significant contributions from climb has been established. Calculations of the strain rate afforded by climb indicate that this form of deformation can contribute significantly to the deformation of TiAl at high temperatures.