Influence of TiB2 Particles on Modification of Mg2Si Eutectic Phase in Al–Zn–Si–Mg–Cu Cast Alloys

Abstract

In this study, the effect of TiB2 particles on the modification of eutectic phase in Al–Zn–Si–Mg–Cu system alloys is investigated. The microstructure showed that an excellent effect can be achieved after the addition of TiB2 particles. The morphology of eutectic Mg2Si changed from large Chinese script to fine polygonal shape with a significant reduction in size. Modified eutectic Mg2Si particles were investigated using an optical microscope and field emission scanning/transmission electron microscope, and it was confirmed that TiB2 particles acted as nucleation sites for the eutectic Mg2Si phase, and the grain size change of Al–Zn–Si–Mg–Cu alloy with increasing TiB2 contents was analyzed by polarizing microscope. The mechanical properties were also improved by the modified of eutectic Mg2Si phase. This manuscript also investigated the reason for the improvement in mechanical properties with the modification of the microstructures. Upon these results, a possible mechanism of eutectic Mg2Si phase modification by the addition of TiB2 particles is proposed.