Transient Anelastic Effects Caused by Diffusion-Controlled Structural Transitions

In this paper, transient effects due to different diffusion-controlled phase (in Fe-Ga alloys) and structural (in Al and Cu alloys) transitions are collected and analyzed. In contrast with well-known transient anelasticity due to diffusionless (martensitic) transitions, transient anelasticity for diffusion-controlled transformations has got much less attention in the literature, most probably due to its weaker effects compared with the sharp transient peaks found in martensitic transitions. In this paper, we consider two types of materials and two types of transient anelasticity. The first group of anelastic effects (transient internal friction peaks) that are analyzed in this paper is associated with reversible and irreversible phase transitions in polymorphic Fe-Ga alloys (bcc-, fcc-and hcp-derived structures: D0 3 → L1 2 → D0 19 → B2/A2), and the second one – by recrystallization (internal friction ‘pseudo’ peaks) in several mainly non-ferrous Al-and Cu-based alloys without polymorphic transitions. It is demonstrated that the main features of existing approaches for transient anelasticity due to martensitic transitions can also be applied to anelastic effects in diffusion-controlled transitions, while quantitative values in these models are significantly different from those for shear transition as they are dependent on diffusion processes.