<p>This study investigates the influence of Y content on the microstructure, mechanical properties, and corrosion resistance of extruded Mg-1.5Zn-0.3Mn-<i>x</i>Y (0, 1.0, 2.0, 2.5, 3.0, and 4.0 wt.%) alloys. Results indicate that at extrusion speeds, ratios, and temperatures of 5&#xa0;mm&#xa0;s^-1, 7.7:1, and 350 °C, respectively, the average grain size progressively decreased with increasing Y content, while the volume fraction of dynamically recrystallized regions gradually increased. Complete dynamic recrystallization occurred in alloys with Y contents exceeding 2.0 wt.%. The secondary phases in the alloy primarily comprised Mg₂₄Y₅ and Mg₃Y₂Zn₃, with both phase size and content progressively increasing with Y content. Between 0 and 2.5 wt.% Y, mechanical properties improved with increasing Y content due to combined grain refinement strengthening and secondary phase strengthening. When the Y content exceeded 2.5 wt.%, the increasing proportion of larger secondary phase particles (&gt;1&#xa0;μm) led to a gradual deterioration in mechanical properties. Within the 0-2.0 wt.% Y range, the concurrent reduction in grain size and increase in Y dissolution into the matrix resulted in progressively enhanced corrosion resistance. At Y contents exceeding 2.0 wt.%, the increasing number and volume fraction of secondary phase particles exacerbate micro-galvanic corrosion, progressively diminishing the alloy's corrosion resistance.</p>