High pressure suppressing grain boundary migration in a nanograined nickel

Grain boundaries (GBs) of nanograined metals are prone to migrate when subjected to mechanical loading. In this study, nanograined pure nickel samples with an average grain size of about 70 nm were deformed under pressure of 20 GPa and 43 GPa using a diamond anvil cell. It was found that the average grain size decreased slightly after high pressure compression, which meant high pressure suppressed the nanograin boundaries migration. Extensive extended dislocations with large dissociation width (averagely 5-6 nm) as well as LomerCottrell locks were observed in the high pressure deformed nanograined Ni, indicating that partial dislocation activities dominated the plastic deformation, which may facilitate to relax GBs and thus suppress GBs migration. The finding of this study may help to fabricate stable nanocrystalline metals.

Automated summary

Grain boundary migration in nanograined metals can be suppressed by high pressure compression, where partial dislocation activities play a significant role in plastic deformation, facilitating the relaxation of grain boundaries.