The effect of addition of Sn to copper on hot compressive deformation mechanisms, microstructural evolution and processing maps

Abstract

The high-temperature compressive deformation behavior of a Cu-10wt.% Sn solid solution alloy was studied in the temperature range of 843–993K and in the strain rate range of 10−3 – 10s−1 and the relationships among the flow stress, strain rate and temperature were determined. Based on the data obtained from the compression tests, the deformation mechanism was identified, and the processing maps were constructed. The Cu-10Sn alloy exhibited solute drag creep at low strain rates and high temperatures and power law breakdown (PLB) at high strain rates and low temperatures. In the processing maps, above the temperature of 933K, the alloy did not show flow instability up to a high strain rate of 10s−1 and showed high power dissipation efficiencies (31–35%) even at the very high strain rate of 10s−1. Furthermore, at 993K, the fraction of dynamically recrystallized grains after compressive deformation was as high as 0.83 at 10s−1. These results indicate that the Cu-10Sn alloy exhibits a significantly better hot workability and a higher quality of post-deformation microstructures compared to the pure Cu where dislocation climb creep is the main deformation mechanism. Continuous dynamic recrystallization occurred at 843K, while discontinuous dynamic recrystallization occurred at 993K. Comparison of the current results with the previous work on the Cu-4.9Sn alloy indicates that the increase of Sn concentration in Cu matrix extends the regime of solute drag creep and delays the onset of PLB to a lower temperature and a higher strain rate.