Influence of yttrium element on the microstructure and mechanical properties of Mg-Y-RE alloys

This study systematically analyzed the effects of yttrium (Y) on the microstructure and mechanical properties of Mg-Y-RE alloys, revealing the specific mechanisms by which varying yttrium content influences the alloy's structure and performance. The addition of yttrium significantly improves the microstructure and mechanical properties of Mg-Y-RE alloys; however, its content must be controlled to avoid adverse effects. Analysis using pole figures, inverse pole figures, and orientation imaging microscopy (OIM) showed that as the yttrium content increases, the grain orientation within the alloy gradually transitions from a random distribution to a state with significant texture characteristics. At low yttrium levels (e.g., 0 wt% and 3 wt%), the alloy exhibits uniform grain orientation and a relatively consistent microstructure, which helps enhance the overall performance of the material. However, as the yttrium content increases to 6 wt%, 8 wt%, and 10 wt%, specific oriented grains begin to aggregate, forming pronounced textures that enhance the material’s anisotropy. SEM images further demonstrated the impact of yttrium on the surface morphology of the alloy. Alloys without yttrium have smooth surfaces with no obvious defects, while those with higher yttrium content exhibit more complex surface morphologies, including grain aggregation and the formation of new phases. These changes not only affect the microstructure of the alloy but also significantly influence its mechanical properties. Specifically, the appropriate addition of yttrium can refine grain size and improve the strength and hardness of the alloy. However, excessive yttrium content may lead to localized stress concentrations, thereby reducing the material’s ductility and fatigue resistance.