Diffusion Properties of Internal Interfaces in Bulk Nanocrystalline Materials: Radiotracer Investigation
The radiotracer technique was applied to measure self- (Fe, Ni) and solute- (Ag) grain boundary diffusion in nanocrystalline Fe-40wt.%Ni alloy. The nanocrystalline material was prepared by pressureless sintering of the nanoalloy powders. The nano-sized crystallites were found to be clustered in micrometer-large agglomerates. Two types of internal interfaces with fundamentally different properties exist in the nanomaterial: the grain boundaries between the nanocrystallites and the interfaces between the agglomerates. A complete and consistent model of the diffusion processes in such material is elaborated. Whereas the nanocrystalline boundaries reveal diffusivities, which are similar to those in coarse-grained material, diffusion along interagglomerate interfaces occurs faster by orders of magnitude. This behavior is explained by a nonrelaxed structure of the inter-agglomerate interfaces.
T. Chandra, K. Tsuzaki, M. Militzer , C. Ravindran
S. V. Divinski et al., "Diffusion Properties of Internal Interfaces in Bulk Nanocrystalline Materials: Radiotracer Investigation", Materials Science Forum, Vols. 539-543, pp. 5019-5024, 2007