Grain refinement and modification of an Al–Si–Mg–Ti–Be cast alloy: microstructure and tensile property

In this study, the combined use of grain refinement and modification was studied on a hypoeutectic Al–Si–Mg–Ti–Be cast alloy. The primary α-Al grains were transformed from columnar dendrites in the as-received alloy into fine equiaxed dendrites. Meanwhile, the eutectic Si with irregular morphologies were modified to fine fibrous. The room-temperature ultimate tensile strength is increased by ∼14% from 145 MPa to 165 MPa, while the elongation to fracture is increased from 3% to 5%. The comprehensive enhancement of mechanical properties is due to the synergistic effect of microstructural refinement and isotropic improvement by α-Al grain refinement and eutectic Si modification.