Figure 8.

The variations of grain size with pressure on compression (upper panel) and decompression (lower panel) at room temperature for nano-Ni. The blue triangles indicate the data derived from the experiment before the bulk yielding (up to 1.35 GPa) and the red triangles from the experiment after the bulk yielding (up to 6.05 GPa). The cyan triangles show the room-temperature data obtained from the high P–T experiment up to 7.4 GPa and 1,400 K, and therefore no grain size data can be derived from the room-temperature decompression