Effect of a New Grain Refiner (Al–Ti–Mg–Ce) on Hardness, Tensile, and Impact Properties of Al–7Si Alloy

Through studying the effects of the Al⁻5Ti-x(Mg⁻30%Ce) refiner on the microstructure of the Al⁻7Si alloy, we investigated the hardness, tensile, and impact properties of the Al⁻Si alloy before and after refinement. The refinement results show that Mg⁻30%Ce can improve the refinement effect of Al⁻5Ti on Al⁻7Si, and also refine α-Al and eutectic Si in Al⁻7Si. When 2%Mg⁻30%Ce is added, the refining effect of the aluminum⁻silicon alloy is most obvious. After refinement, the hardness and tensile properties of the Al⁻7Si alloy improve. When 2%Mg⁻30%Ce is added to the refiner, the tensile properties of the Al⁻Si alloy are the best. Dynamic mechanical tests were conducted on refined Al⁻7Si alloy. The impact toughness of Al⁻7Si⁻(Al⁻5Ti-2(Mg⁻30%Ce) improved and the impact toughness reached 34.91 J/cm2, which is 78.7% higher than that of Al⁻7Si⁻(Al⁻5Ti) specimens. The separate Hopkinson pressure bar test results show that, under a high strain rate, the strain rate sensitivity of the prepared Al⁻Si alloy is significant. The specimens of Al⁻7Si⁻(Al⁻5Ti-2(Mg⁻30%Ce) demonstrated the best anti-impact performance at the same velocity.