Thermal stability of Cu-Cr-Zr alloy processed by equal-channel angular pressing

Highlight
• The Cu-1Cr-0.1Zr alloy shows a very good thermal stability up to 550 °C after ECAP.
• A discontinuous recrystallization was found to occur and PSN mechanism was evidenced.
• The annealing texture was found weak and some new components appear.
• Hardening is attributed to the Cr clustering followed by the Cu51Zr14 precipitation.
• Softening is a result of recrystallization and grain growth progressing.

Thermal stability of a Cu-Cr-Zr alloy processed by equal-channel angular pressing up to16 passes was investigated using isochronal annealing ranging from 250 to 850 °C for 1 h. The microstructure, crystallographic texture and micro hardness of samples were characterized through electron back scatter diffraction and Vickers micro hardness measurements. The recrystallized grain size was stable between 250 °C and 500 °C then increased quickly. The achieved mean grain size, after 1, 4 and 16 ECAP passes, was around 5.5 μm. A discontinuous mode of recrystallization was found to occur and a Particle Simulated Nucleation mechanism was evidenced. The evolution of the high angle grain boundary fraction increased notably after annealing above 550 °C. The crystallographic texture after isochronal annealing was similar to that of ECAP simple shear, no change of the texture during annealing was observed but only slight intensity variations. Micro hardness of all Cu–Cr–Zr samples showed a hardening with two peaks at 400 and 500 °C associated with precipitation of Cu cluster and Cu5Zr phase respectively, followed by a subsequent softening upon increasing the annealing temperature due to recrystallization.