Study on Sc Microalloying and Strengthening Mechanism of Al-Mg Alloy

In this study, Al-Mg alloys were prepared by vacuum + argon-protected casting. The effects of Sc microalloying on the microstructure and mechanical properties of Al-Mg alloy were studied. The strengthening mechanism of Al-Mg alloy with Sc was discussed. The results show that the average grain size of as-cast Al-Mg alloy with Sc reaches 36.07 μm, which is 74.4% smaller than that of alloy 1 without refiner and 32.0% of alloy 2 with 0.15% Ti. The alloy with Sc has excellent comprehensive mechanical properties, with a tensile strength of 274 MPa and an elongation of 29.67%, and its tensile strength is 10.6% higher than alloy 1 and 7.9% higher than alloy 2. There exist two kinds of fine particles in as-cast Sc-containing Al-Mg alloy, nucleated particles Al3Sc, and dispersed second-phase particles Al3(Sc, Ti). The main strengthening mechanisms of the as-cast Al-Mg alloy with Sc reveal the solid solution strengthening of Mg and the fine-grain strengthening effect caused by Sc, accounting for 57.7% and 23.9% to strengthening contribution, respectively.