The 2-step (T1 and T2) deformation behaviour of Ni3Al-based single crystals was modelled within the framework of a new constitutive model. A set of formulations which identified thermally reversible and irreversible components of the constitutive variables, and defined the relative significance of the components, was developed. The simulation results captured well the general qualitative trends in the flow behaviour upon re-straining at T2, after pre-straining at T1, for both T1 > T2 and T1 < T2. The results suggested that the dislocation sub-structures, generated at T1, needed to be treated as being partially or fully transferable to plastic flow at T2, at least in the early stages of re-straining, in order to capture all of the major pre-strain effects. In particular, the large strengthening effect at T2, for even a few percent of pre-strain at T1, was obtainable only by controlling the availability of mobile dislocations and sources at T2.

Modelling Plasticity of Ni3Al-Based L12 Intermetallic Single Crystals II - Two-Step (T1 and T2) Deformation Behaviour. Choi, Y.S., Dimiduk, D.M., Uchic, M.D., Parthasarathy, T.A.: Philosophical Magazine, 2007, 87[30], 4759-75