Characterizing an in Situ TiB2 Particulates Reinforced Aluminium- based Composite and its Heat Treatment

Metal matrix composites were fabricated in an Al-6Cu-0.2Mg-1Mn matrix reinforced by particulates of in-situ TiB2 from a reaction process via K2TiF6 and KBF4 salts in the matrix. Different percentage of the TiB2 particulates, 1 wt-%, 3 wt-% and 5 wt-%, respectively, was employed for the composite. A series of heat treatments comprised of solution treatment and aging were carried out on the composites. Phases, microstructures and Vickers’ hardness were revealed for the differently treated composites and Al-6Cu-0.2Mg-1Mn alloy. The results showed that the in-situ TiB2 particulates could improve the structure of the matrix by retarding a directional growth of the matrix grains and forming isometric grains in the matrix. Remelting the composite with 3 wt-% TiB2 tended to weaken TiB2 particulates’ clustering. A significant effect on the refinement of the grains was observed when the content of TiB2 particulates was increased from 0 to 5 wt-%. And the Vickers’ hardness of the differently treated composites with 3 wt-% or 5 wt-% TiB2 was higher than that of the corresponding Al-6Cu-0.2Mg-1Mn alloys. The composite's precipitation rate was accelerated with the increase of the content of TiB2 particles during aging at 170°C