Grain growth in nanocrystalline nickel films at low temperature and stress

The influence of temperature and stress on grain growth was investigated in nanocrystalline nickel thin films in situ inside a transmission electron microscope. Independently, temperature and stress did not show any appreciable effect. However, concurrent loading at only 20% of melting temperature and 20% of yield stress resulted in significant grain boundary mobility and grain growth. We propose that grain growth in nanocrystals is a stress-heterogeneity- relieving mechanism that may not necessarily be associated with plasticity as proposed in the literature.