EFFECT OF Y ON THE MECHANICAL PROPERTIES AND CORROSION RESISTANCE OF AS-EXTRUDED Mg-4Sn ALLOYS

In this study, the effects of Y element on the microstructure, mechanical properties and corrosion resistance of an extruded T4 alloy at room temperature were studied by comparing the as-extruded Mg-4Sn (T4) and Mg-4Sn-1Y (TW41) alloys. The results showed that the second phase of the as-extruded T4 alloy is mainly the Mg2Sn phase, while the ternary MgSnY and Mg2Sn phases mainly precipitate after the addition of Y element. Incomplete dynamic recrystallization of the two alloys occurs during the extrusion process, and the addition of Y element can promote dynamic recrystallization and refinement of the grains in T4 alloy. At room temperature, TW41 alloy has higher strength compared to T4 alloy, with tensile and yield strengths of 228 MPa and 165 MPa, respectively, but the elongation and corrosion resistance are reduced. Grain refinement is believed to play the key role in improving the yield strength of TW41 alloy, while the deterioration of the corrosion resistance of TW41 alloy is mainly attributed to the increase in the grain boundary density caused by grain refinement, accelerating the dissolution of the alloy anode.