Fig. 1. Contour maps showing strain rate sensitivity m at different strain levels.

Fig. 2. Initial microstructure of grain and γ′ precipitates in as-HIPed A1 sample: (a) EBSD IPF image; (b) γ′ precipitates morphology.

Fig. 3. Shape changes of P/M superalloy samples after compression with different height reductions.

Fig. 4. Photos of specimen with different height reductions during isothermal compression at 1025 °C/10-3 s-1 condition.

Fig. 5. True stress-true strain curves of isothermal compression at (a) 1000 °C and (b) 1025 °C with strain rate of 10-3 s-1.

Fig. 6. Experimental and corrected flow curves of isothermal compression at (a) 1000 °C and (b) 1025 °C with strain rate of 10-3 s-1.

Fig. 7. IPF images of specimens deformed at different conditions.

Fig. 8. Distribution of equivalent grain size of specimens deformed at (a) 1000 °C and (b) 1025 °C with strain rate of 10-3 s-1 and (c) average grain size of specimens deformed with different height reduction.

Fig. 9. EBSD local misorientation images of P/M superalloy samples compressed at 1000 °C/10-3 s-1 and 1025 °C/10-3 s-1 with different height reductions, wherein different colors in rang of 0° to 5° represent different misorientations as indicated by the color bar.

Fig. 10. TEM images of P/M superalloy samples compressed at 1000 °C/10-3 s-1 and 1025 °C/10-3 s-1 with different height reductions.

Fig. 11. Montaged TEM image of P/M superalloy sample compressed at 1025 °C/10-3 s-1 with 80% height reduction.

Fig. 12. (a) Global and (b) local schematic images showing sliding of grain boundary between grains A and B.

Fig. 13. Montaged TEM image showing interactions between dislocations and γ′ precipitates in sample compressed at 1025 °C/10-3 s-1 with 80% height reduction.