Figure 7.

The normalized applied strain plotted as a function of pressure for nano-Ni (red lines) and micron-Ni (blue lines) during loading (solid lines) and unloading (dash lines). The left panel is for the low-pressure experiment up to 1.4 GPa (before the “macro/bulk” yield) and the right panel for the experiment at higher maximum pressure (after the “macro/bulk” yield). For both panels, the plotted lines represent the averaged strains derived from four different lattice planes (111, 200, 220, and 311). The average strains at the highest pressures,P_max, are listed in the inserted boxes. The plots illustrate two important mechanical performances: the strain recoverabilityRec. = and the loading–unloading hysterisis loops, which are correlated to the high-pressure works driving energy dissipation and can reveal the degree of mechanical fatigue. The plots show clear differences between nano-Ni and micron-Ni in both mechanical qualities