Fig. 1. Schematic of TM-TM20V-TM12Mo diffusion multiple. The red box is the research area, and the black dot matrix in the box is nanoindentation, with a total of 15 × 15 dots and an interval of 100 μm.

Fig. 2. Distribution of alloy composition (Mo and V contents) corresponding to diffusion multiple nanoindentation lattice.

Fig. 3. SEM images of TM-xMo-yV alloy quenched at 1100 °C in different positions (compositions) of diffusion multiple.

Fig. 4. SEM images of TM-xMo-yV alloy at different positions (compositions) of diffusion multiple after aging at 600 °C.

Fig. 5. Hardness distribution of the TA-xMo-yV alloy at different positions in the red box area in Fig. 1. (a) Quenched at 1100 °C, the positions of a, b, and c correspond to Fig. 3(a-c) respectively; (b) aging at 600 °C, corresponding to Fig. 4.

Fig. 6. (a, b) TEM images of forged TM-6Mo-3V alloy quenched at 1100 °C and selected electron diffraction in the [113] β direction, (c, d) 600 °C aging TEM morphology and selected electron diffraction in [1$\bar{1}$1] the β direction.

Fig. 7. Tensile curve of forged TM-6Mo-3V alloy at 1100 °C solution treatment plus 600 °C aging.

Fig. 8. TEM images of the aged TM-6Mo-3V alloy after tensile deformation: (a) bright field image, (b) curved α phase, (c) selective electron diffraction in the [011] β direction, (d) the accumulation of dislocations in the β phase at the α/β interface induces α phase twinning, (e) Selected area electron diffraction in the [$1\bar{2}1\bar{3}$]α direction.

Fig. 9. Statistical comparison of the number density of α phases in Fig. 4(c, h, l, k) and 4(d, i, m, q, p). The latter is significantly higher than the former.

Fig. 10. Schematic of the pseudo-spinodal mechanism principle. The fluctuation of alloy composition causes the change in free energy, thereby providing the driving force for the precipitation of the α phase. Calloy is the alloy composition, Cαinit is the initial composition of the α phase nucleation, Cαequil is the equilibrium composition of the α-phase, the red arrow represents the composition fluctuation, and the green arrow represents the driving force for the β to α transition caused by the composition fluctuation.

Fig. 11. (a) Free energy curves of the α- and β-phases of TM-xMo-yV (x = 1, 3.2, 5.9, 7.5) alloy calculated by TC at 600 °C; (b) Enlarged view of Fig. 11(a), where the free energy curve intersection point C0 is TM-1Mo-7.6V, TM-3.2Mo-5.3V, TM-5.9Mo-2.8V, and TM-7.5Mo-1.8V, corresponding to Fig. 4(i, m, p, q), respectively.

Fig. 12. Composition of α and β phases in TM-3Mo-xV (a, b) and TM-3V-xMo (c, d) alloys calculated with CALPHAD as a function of Mo and V contents (corresponding to the second column and second row of Fig. 4).

Fig. 13. (a) Variation of the alloy yield strength calculated by Eq. (7) with the α-phase fraction and thickness and the experimental results (the experimental results are obtained from the hardness). In Eq. (7), $\text{M}{{\text{o}}_{i\beta }}$ and ${{\text{V}}_{i\beta }}$ are set to constant 10. (b) The cross-sections where the α phase thickness is 50 and 500 nm.