Phase Transformations in Copper—Tin Solid Solutions at High-Pressure Torsion

Phase transformations of some Hume-Rothery phases (electron compounds) to others in a copper-tin system subjected to high-pressure torsion were detected in our previous work [B.B. Straumal et al., JETP Lett. 100 , 376 (2014)]. In particular, the torsion of the ζ + ε phase mixture at high pressure led to the formation of the δ + ε phase mixture, as after long-term annealing in the temperature interval T eff = 350–589°C. In this work, it has been shown that the high-pressure torsion of α-solid solutions of tin in copper results in the final stable solid solution whose composition is independent of the composition of the initial α phase before high-pressure torsion. The final composition is the same as after long-term annealing at the temperature T eff = (420 ± 10)°C. The rate of high-pressure torsion-induced mass transfer is several orders of magnitude higher than the rate of conventional thermal diffusion at the treatment temperature T HPT and is close to values at T eff . This occurs because high-pressure torsion increases the concentration of lattice defects and this increase is in turn equivalent to an increase in the temperature.