Role of grain-boundary diffusion in the grain growth in nanocrystalline nickel

The grain growth in a nanocrystalline nickel during nonisothermal annealing is studied by differential scanning calorimetry (DSC) and transmission electron microscopy. Nanocrystalline nickel is prepared by electrodeposition at a pulsed voltage. Its nonisothermal annealing is accompanied by anomalous grain growth; at a temperature corresponding to a DSC peak, a bimodal grain structure forms. The processing of DSC signals in terms of the Avrami formalism permits the grain growth activation energy to be determined, which is found to be close to the activation energy of grain-boundary self-diffusion. The anomalous grain growth creates conditions such that grain-boundary diffusion is a controlling stage of the process.