Hot deformation behavior of in situ nano ZrB2 reinforced 2024Al matrix composite

The hot deformation behavior of in situ 5 wt.% nano ZrB2/2024Al composite was studied at deformation temperatures of 350-450 degrees C and strain rates of 0.001-10 s(-1). The results show that the flow stress depends strongly on the deformation temperature and strain rate, and especially exhibits a strain hardening at high temperature and high strain rate, related to the introduction of nanoparticles (ZrB2: 15-40 nm). The kinetic equation was constituted and indicates that the key deformation mechanism is dynamic recrystallization (DRX), which is in accordance with the deformed microstructures. The processing maps (PMs) exhibit two deterministic domains of domain 1 (380-410 degrees C/0.018-0.032 s(-1)) and domain 2 (440-460 degrees C/0.075-0.56 s(-1)), where domain 2 has the higher power dissipation efficiency, higher strain rate, meaning more safety and higher efficiency for the hot processing. At the same time, the deformed specimen exhibits equiaxed and fine grains in domain 2, i.e., a typical DRX structure, thus is suggested as the optimum hot processing window for this nanocomposite. (C) 2015 Elsevier Ltd. All rights reserved.