Effect of TiB2 addition on microstructure of spray-formed Si-30Al composite

An in situ reaction and spray forming technique were employed in the synthesis of 2% TiB2/Si-30Al composite. The formation mechanism of TiB2 particulates was explained based on thermodynamic theory. The modification of the primary Si in the Si-30Al alloy was interpreted in the light of the knowledge of atomic diffusion. The experimental results show that adding 2% TiB2 to the Si-30Al alloy can effectively refine the primary Si. Moreover, the coarsening and growth of primary Si phase in its semi-solid state was retarded effectively due to the existence of the TiB2 particulates.