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Overcoming the strength-plasticity trade-off by regulating grain size and precipitation behavior remains a central challenge in magnesium (Mg) alloy development. This study investigates the synergistic improvement of strength and ductility in Mg alloys by partially substituting Gd with Nd and Y to tailor precipitation behavior and grain structure. Using extruded VK61 as the base alloy, the addition of Nd (VEK421) transformed Mg5 Gd precipitates into Mg5 (Gd, Nd), preserving the original phase structure. Further alloying with both Nd and Y (VWEK4111) refined the precipitates to nanoscale Mg24 (Gd, Y, Nd) 5. Compared to VK61, precipitate sizes in VEK421 and VWEK4111 were reduced by 25.8 % and 51.4 % and precipitate area fractions were increased by 12.6 % and 24.6 %, while grain sizes decreased by 34.4 % and 56.3 %, respectively. The alloying elements also influenced slip behavior, with Nd and Y suppressing basal slip and promoting non-basal slip activity, thereby improving deformation uniformity. Tensile tests showed that VEK421 achieved a yield strength (YS) of 184.9 MPa and elongation (EL) of 33.6 %, representing increases of 15.6 % and 40.6 % over VK61. VWEK4111 further improved YS to 220.6 MPa (up 37.8 %) and EL to 26.9 % (up 15.5 %). These enhancements are attributed to grain refinement and activation of pyramidal slip. This work demonstrates an effective alloy design strategy for cost-efficient, high-performance Mg alloys via microstructure and precipitation engineering.
Zhao et al. (Sat,) studied this question.