Structural and mechanical aspects of dynamic precipitation in some precipitation hardenable alloys.

Recent experimental results and structural analysis of hot deformation processes in some precipitation hardenable alloys, with reference to experiments on dynamic precipitation presented in professional literature, are reviewed. In particular, the interaction of continuous and discontinuous precipitation in Cu-Ni-Si-Cr-Mg and Cu-Ti alloys was discussed on the basis of mechanical tests and structural observation results. Nonuniform deformation and dynamic coarsening of discontinuously grown particles within shear bands has followed the flow stress maximum during hot deformation of solution treated alloys at intermediate temperatures and was responsible for efficient material softening at larger strains. Dynamic precipitation in an Al-Mg-Si alloy was found to affect the strain rate sensivity. It was suggested that the strain rate sensivity, in the presence of nonuniform mode of deformation, could be accepted as a parameter which describes a specific mechanical property for a hot material only. Any analysis of dislocation movement affected by diffusion controlled solutes interaction or dynamic precipitation, as was suggested in the literature, seems to be doubtful. Hot deformation of copper and Cu-Cr alloy was found to result in an increase of the structural stability and, in consequence, mechanical properties of the material during post deformation annealing/aging.