Acoustic emission experiments on creeping single crystals had shown that the dynamics of an assembly of interacting dislocations became self-organized into a scale-free pattern which was characterized by power-law distributions of avalanche sizes. Here, the possible incidence of temperature and microstructure upon this emerging pattern was investigated. The temperature did not modify the nature of the critical dynamics. However, it seemed to modify the avalanch relaxation, due to dislocation–phonon interactions. Tests on polycrystals revealed the role played by grain boundaries as barriers to dislocation motion which hindered the emergence of the scale-free pattern, as well as the role of kinematic hardening as a polarized internal stress.

Dislocation Avalanches - Role of Temperature, Grain Size and Strain Hardening. T.Richeton, J.Weiss, F.Louchet: Acta Materialia, 2005, 53[16], 4463-71