Investigations on the Cr Phase Solubility Increasing and Dynamic Recrystallization Induced by Adiabatic Shearing in Cu-15Cr In-Situ Composite

The mechanisms of Cr phase solubility increase and dynamic recrystallization of the Cu matrix in the adiabatic shear band (ASB) of Cu-15Cr in situ composites were, to our knowledge, first investigated in this paper. Quantitative calculations showed that the solubility of Cr phases increased by 0.51 at.% and 1.0 at.% at the edge and center of the ASB, respectively. Thermodynamic analysis revealed that the free energy difference between the Cr phases and Cu matrix was the thermodynamic condition for the dissolution of the Cr phases. Kinetic analysis showed that the dissolution of Cr phases was the result of combined effects of high dislocation density, high adiabatic temperature, high cooling rate, and additional tensile stress. The adiabatic temperature (660 K) and cooling rate (3000.0 K/s) were higher, and the Cr phase was subjected to greater additional tensile stress in the center than those (temperature: 443 K, cooling rate: 2538.5 K/s) at the edge of the ASB. Hence, the increased solubility of Cr phases in the center of the ASB was higher than that at its edge. Additionally, dynamic recrystallization occurred in the Cu matrix in the center of the ASB, and the evolution mechanism was also analyzed from the thermodynamic-kinetic view.