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Page 12 of 17 Cheng et al. J. Mater. Inf. 2025, 5, 53 https://dx.doi.org/10.20517/jmi.2025.61

Table 5. The expanded decision space used for the inverse design of high-performance Mg-Gd-based alloys
Composition (wt.%) Processing parameters
Range
Gd Y Zn Mn ST (°C) St (h) ET (°C) ER
Min 0 0 0 0 400 5 290 5
Max 15 7 4 2 560 30 460 40
ST: Solid solution temperature; St: solid solution time; ET: extrusion temperature; ER: extrusion ratio.

Figure 7. Comparison of the predicted, target, and experimental mechanical properties of (A) Alloy 1 and (B) Alloy 2.

Using the established RF-NSGA inverse design model, two Mg-Gd-based alloys with high strength and
ductility were designed. The target properties for the two alloys were set as UTS values of 450 and 250 MPa,
paired with EL values of 5% and 40%, respectively. To ensure design stability, five independent inverse
design runs were conducted. The optimized chemical compositions and processing parameters were then
selected by comparing their deviations from the target values.

Figure 8 shows the Pareto optimal frontiers calculated by the inverse model for the two alloys. In
comparison, the non-dominated solutions for high-strength alloys are rather scattered, indicating an
increased challenge in the balance between strength and ductility. The designed chemical composition and
process parameters for both alloys are shown in Table 6. Accordingly, the high-strength alloy is Mg-11.5Gd-
6.0Y-1.0Zn-0.2Mn (VW126, wt.%) containing relatively high RE content of 17.5 wt.%. The high-ductility
alloy is Mg-2.5Gd-1.0Zn (VZ31, wt.%) containing relatively low RE content of 2.5 wt.%. It should be noted
that the UTS of the designed VW126 alloy is slightly below the target value (~11.3 MPa) due to the limited
data available for high-strength alloys within the established dataset.

Based on the predictions from the inverse design model, VW126 and VZ31 alloys were prepared for
mechanical property tests. The actual compositions of the designed alloys and the process parameters
applied in practical experiments are shown in Table 7. It should be noted that the ER applied in the
experiments was slightly different from the designed ones for simplification. The tensile stress-strain curves
of the two alloys at room temperature are illustrated in Figure 9. Three repetitive tests were performed for
each alloy to ensure reliability. The averaged UTS and EL of the VW126 alloy were experimentally
measured to be 417 MPa and 3.2%, respectively, while those of the VZ31 alloy were 223 MPa and 34.0%. For
comparison without any potential uncertainties, the RF forward model was applied to predict the
mechanical properties for the designed alloys with the inputs shown in Table 7. Figure 10 compares the
experimentally measured mechanical properties with the target values, the predictions from the RF-NSGA
inverse design model, and the RF model predictions based on the experimental input parameters. It is clear