Hot deformation behavior and mechanism of hybrid aluminum-matrix composites reinforced with micro-SiC and nano-TiB2

The hot compression tests of hybrid aluminum-matrix composites reinforced with micro-SiC and nano-TiB2 were performed at deformation temperature of 350-500 degrees C and strain rates of 0.001-1s(-1) on Gleeble-3500 system. The corresponding deformed microstructures were characterized by electron back scattered diffraction (EBSD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the true stress increased rapidly with the increase of the true strain and then stabilized or decreased slightly after the true stress reaches the peak value. The peak stress levels increased with the decrease of deformation temperature and the increase of strain rates. The flow stress behaviors of the hybrid composites can be described by the sine-hyperbolic Arrhenius equation with the deformation activation energy of 269.7 kJ/mol. The main flow softening mechanism of the hybrid composites is dynamic recovery (DRV), accompanied by partial dynamic recrystallization (DRX). In particular, the addition of TiB2 nanoparticles promotes dislocation pile-up and simulates DRX nucleation. (C) 2018 Elsevier B.V. All rights reserved.