A new nucleation mechanism of primary Si by peritectic-like coupling of AlP and TiB2 in near eutectic Al–Si alloy

The effect of TiB2 particles on phosphorous modification efficiency in near eutectic Al–Si alloy and a new nucleating mechanism was studied in this paper. The results show that it presents remarkable phosphorous modification effect after the addition of 0.2%Al–5Ti–1B alone into the Al–12.6Si alloy, the modification efficiency can be improved and the sizes of primary Si can be obviously refined after the addition of 0.2%Al–5Ti–1B in the P modified Al–12.6Si alloy. EPMA shows there is a coupling of AlP and TiB2 particles in the centre of primary Si, and a new nucleation mechanism of primary Si by peritectic-like coupling of AlP and TiB2 was presented. The formation mechanism of peritectic-like coupling of the particles was also discussed.