Influence of Si, Ti, and Cu as alloying elements on the wettability and reactivity of an Al/B4C system

The wettability and reactivity of Al alloys and B4C are of vital importance in the production of B4C-reinforced Al-matrix composites. However, previous research has primarily focused on pure Al/B4C systems, with little focus on alloying elements. In this paper, we investigated the influence of Si, Ti and Cu as alloying elements on the wettability and interfacial reactivity of an Al/B4C system using improved sessile drop methods. The B4C substrate was not wetted by molten Al at 700−1000 °C, with initial contact angles higher than 100°. However, rapid spreading was observed in the initial stages due to the formation of Al3BC and Al4C3. Si had a noticeable effect on the interfacial wettability only at levels of 15 wt% or above, with the interfacial products changing from Al3BC and AlB2 to SiC-dominated phases. The addition of Ti to Al led to the formation of TiB2-dominated interfacial products, which replaced the Al3BC and AlB2 phases, with the spreading kinetics mainly controlled by interfacial reactions in the early stages and the diffusion of Ti from the bulk of the drop to the triple line in the later stages. The addition of Cu had a negligible effect on the wettability but slightly weakened the formation of AlB2 by promoting substrate dissolution.