Identification of different deformation mechanisms and the nature of transitions between them

Several formulations have been proposed linking strain accumulation with ti me, stress temperature and microstructural features of a given material. Mo re detailed approaches have considered distinctive mechanisms of deformatio n and their predominating influence in specific regimes. The importance of identifying the boundaries of these regimes is demonstrated. Their distingu ishing features are emphasised and shown to have important consequences. Tr ansitions between different regimes however may not be sharp. The nature of the transition between deformation occurring by lattice dislocation moveme nt and by the stress directed diffusion of vacancies is analysed and its pr actical implications are considered.