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

Thermal stability of a Cu-Cr-Zr alloy processed by equal-channel angular pressing up to 16 passes was investigated using isochronal annealing ranging from 250 to 850 degrees 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 degrees C and 500 degrees C then increased quickly. The achieved mean grain size, after 1, 4 and 16 ECAP passes, was around 5.5 mu m. 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 degrees 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 degrees C associated with precipitation of Cu cluster and Cu5Zr phase respectively, followed by a subsequent softening upon increasing the annealing temperature due to recrystallization. (C) 2016 Elsevier Inc. All rights reserved.