On the kinetics of grain growth inhibited by vacancy generation

Effect of the oxygen content on the structure, morphology and oxidation resistance of Cr–O–N coatings

“…As can be seen, both annealing in air and vacuum leads to a sharp increase of D ave for the samples A, while for the coatings C and F, having higher O concentrations, the grain growth is significantly hindered. The surprising dependence of the recrystallization behavior on O rel could be attributed to several factors such as triple points effect [25], boundary surface stabilization observed in nanocrystalline alloys [26], solute [27] or vacancies pinning effect [28]. In particular, a stabilizing effect at decreasing D ave may be the consequence of the high ratio between the boundary area and the volume of the crystallites.…”

“…This leads to a higher number of triple points boundary configurations [25] and to a solute enrichment at the boundary, which reduces the surface energy of the nanocrystallites resulting in the formation of metastable Gibbs free energy minima [26]. Furthermore, the increase of the interface area with decreasing D ave , results in the enhancement of the pinning effect from solute atoms at the grain boundaries [27] or vacancies [28]. All these explanations are consistent with the increase of the thermal stability with decreasing D ave observed in our Ostabilized coatings.…”

Grain growth stagnation in fully dense nanocrystalline Y2O3 by spark plasma sintering

“…Estrin et al [59,60] explained this reduced (linear) grain growth in terms of the free volume present at the grain boundaries. The vacancies associated with this free volume at the grain boundaries diffuse into the crystal, increase its vacancy concentration and thus its free energy.…”

Characterization and Determination of Elastic Property of High-Density Nanocrystalline Gold Prepared by Gas-Deposition Method

“…The increase in 3ðÁL=L 0 À Áa=a 0 Þ at T ann between 300 and 400 K is compatible with the view that the excess vacancy type defects are associated with the structural relaxation before the grain growth. 8,9) It is noted that for n-Cu prepared by the electrodeposition method, a small energy release of 3.2 J/mol was observed at around 423 K and supposed to reflect a recovery of the stored strains.…”

“…7) Theoretically, it is suggested that the grain growth process in n-metals would be retarded in comparison with that in the bulk polycrystalline (p-) metals when the excess vacancy type defects contained in the GB regions should move into the constituent crystallites. 8,9) The excess vacancy type defects may play an important role on the thermal stability of the high-density nmetal, as well as the grain growth process.…”