Study of precipitate evolution and recrystallization of β-quenched Zr-Sn-Nb-Fe-Cr-Cu alloy during aging

Electron backscatter diffraction, electron channeling contrast, secondary electron imaging techniques and micro-hardness tests are jointly employed to investigate the precipitate evolution and recrystallization of a Zr-0.85Sn-0.4Nb-0.4Fe-0.1Cr-0.05Cu alloy during aging between 600 and 700 degrees C following beta-quenching treatment. Results show that the implemented quenching produces plate structures with specific orientations. For specimens aged at lower temperature or for shorter time, the plate structures maintain yet second phase particles (SPPs) precipitate along the plate boundaries. For specimens aged at higher temperature or for longer time, recrystallizations are completed. The recrystallized structure presents irregular grain shapes, non-uniform grain sizes and randomly distributed SPPs. In spite of the morphology discrepancies, some recrystallization grains inherit the orientation feature of the prior a plates. With increasing temperature and time, hardness decreases and no hardness peak is observed. Reasons accounting for the formation of different microstructural features are tentatively discussed. (C) 2012 Elsevier B.V. All rights reserved.