Study of the Hall-Petch Dependence in an Annealed Nanocrystalline Iron Thin Film

Abstract

The hardness dependence on grain size of a nanocrystalline iron thin film prepared by sputtering was investigated. The as-deposited film had an initial grain size of 11.4 nm and sections of the film were annealed in a reducing atmosphere furnace to increase the grain size up to 31.5 nm. Hardness was measured by nanoindentation for different grain sizes, and a Hall-Petch plot of hardness versus reciprocal square root of grain size was obtained. This Hall-Petch plot gave a positive slope that was about a factor of seven smaller than the slope obtained from ball-milled iron with grain sizes between 6.0 and 8.5 nm [8].