Microstructure Control and Performance Evolution of Hypereutectic Al–20Mg2Si Alloy by Novel Al–Ca–Sb Masteralloy

Herein, the microstructure control and performance evolution of hypereutectic Al–20Mg 2 Si alloy with the addition of novel Al–3.3Ca–10Sb master alloy are investigated. It is found that AlCa 11 Sb 9 and CaSb 2 compounds are successfully synthesized through in situ melt reaction of masteralloy. With 0.45 wt% Al–3.3Ca–10Sb master alloy addition, primary Mg 2 Si particles in hypereutectic Al–20Mg 2 Si alloy are significantly refined from more than 150 μm to 10.7 μm, which are accompanied with the 3D morphologies changing from dendrites to octahedrons. After heat treatment, Brinell hardnesses of Al–20Mg 2 Si alloys are remarkably improved to 112 HB. Furthermore, it is also found that the cooling rate of Al–3.3Ca–10Sb master alloys has certain influence on the refinement effect of Al–Mg 2 Si alloys. The excellent complex modification of this master alloy on Al–20Mg 2 Si alloy can be attributed to the existence of CaSb 2 particles as the heterogeneous nucleation sites of Mg 2 Si particles and the inhibiting growth effect of residual Ca atoms adsorbed on the surface of Mg 2 Si phase.