Anelasticity study on interfaces of nanocrystalline Au and nanoporous Au

The grain boundary region and pore play an essential role in nanostructured materials. In the present study, nanoporous (np-) Au prepared by dealloying (DA np-Au) is studied by means of the anelasticity measurement referring to the nanocrystalline (n-) Au prepared by the gas-deposition method (GD n-Au). In GD n-Au->0.99 (the subscript, >0.99, denotes the relative density of the specimen referring to the bulk density), the linear increase in the internal friction above 200 K (Q(>200) (-1)(K)) and a broad peak at about 100 K (P-L) are observed. In GD n-Au-0.81 containing nanopores, broad peaks atabout 220 K (P-H1) and 260 K (P-H2)as well as P-L and Q(>200) (-1)(K) are observed. In DA np-Au-0.4, P-L, P-H2 and no Q(>200) (-1)(K) are observed. Densification of DA np-Au-0.4 by pressing causes a significant increase in both P-H1 and P-H2, and annealing at 360 K cancels the effect of pressing. These results are discussed in the light of the characteristic grain boundary properties in nanostructured materials. (C) 2009 Elsevier B.V. All rights reserved.