Hall-petch Hardening in Pulsed Laser Deposited Nickel and Copper Thin Films

Very fine-grained Ni and Cu films were formed using pulsed laser deposition on fised silica substrates. The grain sizes in the films were characterized by electron microscopy, and the mechanical properties were determined by ultra-low load indentation, with iinite-element modeling used to separate the properties of the layers from those of the substrate. Some Ni films were also examined after annealing to 350 and 450°C to enlarge the grain sizes: These preliminary results show that the observed harnesses are consistent with a simple extension of the Hall-Petch relationship to grain sizes as small as 11 nm for Ni and 32 nm for Cu.