Effects of multi-directional forging on the microstructure and mechanical properties of TiB2 particulate reinforced 6061Al composite

Abstract

TiB2 particulate reinforced 6061Al (TiB2/6061Al) composite was fabricated by hot press sintering, and multi-directional forging was further applied to enhance the microstructure and mechanical properties. The results showed that TiB2/6061Al composite with high sintering quality was achieved. Both TiB2 particles and forging promoted the occurrence of dynamic recrystallization, contributing to the refinement of grain structure. The degree of dynamic recovery was also enhanced as the increase of forging pass, which retarded the further reduction of grain size. Al(Cr, Fe)Si phase having a pinning effect on the movement of dislocations was found in Al matrix. The edged dislocations and lattice distortion were introduced by forging, and the highest density of edged dislocations was achieved after 3 passes. Moreover, the Mg-rich layer formed at the interface between TiB2 particle and Al matrix, indicating a good bonding quality of the interface. Due to the effects of load transfer, grain refinement, and dislocation strengthening, the hardness and ultimate tensile strength of the composite increased by 48.1 % and 27.4 %, respectively. However, as the forging pass increases from 3 to 9, the increments of hardness and strength were not obvious, since the softening effect attributed to dynamic recovery became dominant.