Fig. 1. Dimension of samples used for tensile tests.

Fig. 2. Variation of hardness vs aging time, corresponding to different samples of the Cu-0.4?wt.% Sc alloys: (a) the RTR sample with subsequent aging, (b) the CR sample with the subsequent aging process.

Fig. 3. The variation of mechanical properties corresponding to different samples of the Cu-0.4?wt.% Sc alloys with different aging time, (a) yield strength of RTR sample with subsequent aging, (b) yield strength of CR sample with subsequent aging process, (c) yield strength and (d) tensile strength of RTR and CR samples.

Fig. 4. Variation of electrical conductivity corresponding to different samples of the Cu-0.4?wt.% Sc alloys: (a) the RTR sample and (b) the CR sample with the subsequent aging process.

Fig. 5. Comparison of properties of various Cu alloys and designed alloy.

Fig. 6. XRD spectrums of the Cu-0.4?wt.% Sc alloys after aging at 400?°C for different time: (a) the RTR sample and (b) the CR sample with the subsequent aging process.

Fig. 7. (a) The line-scanning photograph of CR Cu-0.4?wt.% Sc alloy aged at 400?°C for 8?h, and (b) its corresponding element distribution along the red line in (a).

Fig. 8. (a) Bright-field TEM photograph of RTR sample aged at 400?°C for 0.5?h, (b) HRTEM photograph of the precipitates in the figure (a) and the corresponding diffraction patterns (c) along [011]α zone axis, (d) bright-field TEM photograph of RTR sample aged at 400?°C for 1?h, (e) and (g) HRTEM photographs of the precipitates in the figure (d) and corresponding diffraction patterns (f) and (h) along [011]α zone axis.

Fig. 9. (a) Bright-field TEM photograph of RTR sample aged at 400?°C for 4?h, (b) Bright-field TEM photograph of RTR sample aged at 400?°C for 8?h, (c) HRTEM photograph of the precipitates in the figure (a) and the corresponding diffraction patterns (d) along [001]α zone axis, (e) HRTEM photograph of the precipitates in the figure (b) and corresponding diffraction patterns (f) along [011]α zone axis.

Fig. 10. (a) Bright-field TEM photograph of CR sample aged at 400?°C for 1?h and the HRTEM photograph (b), (c) HRTEM photograph of the precipitates in the figure (a) and the inset (d) of diffraction patterns along [011]α zone axis, (e) Bright-field TEM photograph of CR sample aged at 400?°C for 2?h, (f) HRTEM photograph of the precipitates in (e) and the inset (g) of diffraction patterns along [011]α zone axis.

Fig. 11. (a) Bright-field TEM photograph of CR sample aged at 400?°C for 8?h, (b) HRTEM photograph of the precipitates in (a) and the inset (c) of diffraction patterns along [011]α zone axis, (d) the corresponding diffraction patterns of (a) along [011]α zone axis, (e) the schematic diagram of (d).

Fig. 12. (a) Atomic unit-cell photograph of the Cu4Sc phase and the corresponding diffraction patterns (b) along $[11 \overline{3}]$ zone axis obtained by software, (c) the multiple cells photograph of the Cu4Sc phase.

Fig. 13. The statistical distribution of precipitate size in Cu-0.4?wt.% Sc alloys, (a) RTR sample and (b) CR sample aged at 400?°C for 8?h.

Fig. 14. Dynamic curves of precipitation rate of the Cu-0.4?wt.% Sc alloys aged at different temperatures, (a) the RTR sample, (b) the CR sample with the subsequent aging process.

Fig. 15. Probability density function vs. precipitation radius of the RTR sample and CR sample aged at 400?°C for 8?h.