Study on the microstructure, recrystallization, and mechanical properties of hot-press sintered (TiC + B4C)/6061Al composites during hot rolling

Abstract

Hot rolling is a vital secondary processing technique for aluminum matrix composites. To explore the forming mechanism of (TiC+B4C)/6061Al composites during hot rolling, the 6061Al and (TiC+B4C)/6061Al composites were fabricated via vacuum hot-press sintering followed by hot rolling. The results show that reinforcing particles changed the distribution of Si and resulted in the in-situ generation of SiC in hot-rolled (TiC+B4C)/6061Al composites. During hot rolling, reinforcing particles inhibited the elongation and refined the size of Al grains, and contributed to further enhancing the hardness and strength of hot-rolled 6061Al. With the hot rolling reduction rate increasing, the hardness and strength of hot-rolled (TiC+B4C)/6061Al composites improved, and the refinement effect of reinforcing particles intensified. Both reinforcing particles and hot rolling exhibited effects on the recrystallization behavior of 6061Al during hot rolling, primarily through particle induced nucleation mechanism and strain induced grain boundary migration mechanism. Remarkably, the strength achieved by hot-rolled (TiC+B4C)/6061Al composites at a 20% hot rolling reduction rate rivals that of hot-rolled 6061Al at an 80% hot rolling reduction rate, while still preserving high plasticity. Hot-rolled (TiC+B4C)/6061Al composites predominantly exhibited the ductile fracture of aluminum matrix and cleavage fracture of particles, and the ductile fracture characteristics gradually weakened with the hot rolling reduction rate increasing. The dislocation increment strengthening mechanism contributed the most to the strength improvement of hot-rolled (TiC+B4C)/6061Al composites. This study can provide valuable insights into aluminum matrix composites.