ROOM-TEMPERATURE CREEP-BEHAVIOR OF NANOCRYSTALLINE NICKEL PRODUCED BYAN ELECTRODEPOSITION TECHNIQUE

Deformation processes of nanocrystalline (6-40 nm) nickel produced by an electrodeposition technique were studied. First, the results of uni directional tensile tests were discussed with respect to the deviation from the Hall-Petch relationship. It was suggested that such a mechan ical behavior exhibited by nanocrystalline materials could be describe d by a composite model proposed previously. Further experimental work on static and dynamic creep tests under the load control condition sho wed that nanocrystalline nickel electrodeposits exhibited a significan t room temperature creep behavior. It appeared that grain boundary sli ding and diffusive matter transport within the intercrystalline region played an important role in terms of deformation mechanisms of nanocr ystalline materials. The contributions of dynamic creep to stress-stra in behavior and, in turn, to the assessment of the Hall-Fetch relation ship for nanocrystalline materials are discussed. (C) 1997 Elsevier Sc ience S.A.