The effect of 60MeV 12C bombardment upon nanocrystalline samples was studied. It was found that the bombardment-induced defects were thermally unstable, due to the presence of a large volume fraction of grain boundaries.

Accumulation and Recovery of Defects in Ion-Irradiated Nanocrystalline Gold. Y.Chimi, A.Iwase, N.Ishikawa, M.Kobiyama, T.Inami, S.Okuda: Journal of Nuclear Materials, 2001, 297[3], 355-7