Dependency of annealing behaviour on grain size in Al–TiC composite produced by accumulative roll bonding

Abstract

This work investigates the effect of grain size on annealing behaviour in both coarse-grained and ultrafine-grained Al–TiC composite processed by accumulative roll bonding (ARB). Microstructural analysis indicates that annealing behaviour of the specimens are essentially determined by the level of strain accumulation or number of ARB cycles, i.e., recrystallization phenomenon are accelerated by increasing the level of strain accumulation or number of ARB cycles. Microstructure analysis illustrates that annealing treatment at 200 or $250{^{\circ }}\hbox {C}$ for the 1-cycle ARB-processed Al–TiC composite having coarse grains does not lead to the recrystallization phenomenon, indicating that only recovery appears. In contrast, partial recrystallization occurred after annealing at $250{^{\circ }}\hbox {C}$ in the 7-cycle ARB-processed Al–TiC composite having ultrafine grains. Furthermore, annealing treatment significantly enhanced elongation for both ultrafine as well as coarse-grained Al–TiC composites in spite of the fact that yield and ultimate strength decreased during annealing treatment. The results proved that yield strength and tensile strengths for both 1-cycle and 7-cycle ARB-processed Al–TiC composites gradually decreased by annealing treatments between 200 and $300{^{\circ }}\hbox {C}$. In contrast, ultimate elongation drastically improved by about 100% after annealing at the aforementioned conditions.