Effect of In-Situ TiB₂ Particles on the Microstructure of Spray-Formed 70Si-Al Alloy

Abstract

A novel reactive technique has been employed to fabricate 2.0 mass%TiB₂/70Si-Al composite. The growth behavior of primary Si phase in the 2.0 mass%TiB₂/70Si-Al composite was investigated when the composite was heated in its semi-solid state. Both theoretical and experimental results have shown that the in-situ TiB₂ particles can refine effectively the primary Si phase and restrain the Si phase growth. The coarsening rate constant of the 2.0 mass%TiB₂/70Si-Al composite was calculated as 3.69×10⁻¹⁸ m³/s, which is less than that of 70Si-Al alloy (7.6×10⁻¹⁷ m³/s), suggesting that the in-situ TiB₂ particles can effectively pin the grain boundaries and arrest the migration of liquid film when the composite was heated in its semi-solid state.