Two-phase theory for the superplastic flow

We discuss a theoretical approach to the stress induced motion of vacancies in a polycrystalline material and its connection with superplastic flow, put forward recently by us. After introducing an alternate formulation, the theory is applied to explain the temperature dependent stress-strain rate curves exhibited by some representative alloys. The agreement with experiment is remarkable. We also employ it to study the rate of cavity growth in two superplastic copper alloys that exhibit particularly strong cavitation.