Mechanical properties of electrodeposited nanocrystalline nickel

In this paper, dense bulk nanocrystalline (nc) nickel electrodeposits with various grain sizes were produced by using high frequency pulse current and strong electrolyte flushing. The effects of the grain sizes on the mechanical properties were discussed for room and a medium temperature. It was found that the properties of the deposited nickel such as of microhardness, corrosion resistance and yield stress (at room temperature and 473 K) were improved substantially with the decrease in the grain size. A deviation of yield stress from the Hall-Petch relationship for ne nickel was observed when the grain sizes were decreased to less than 70 nm at room temperature. A low yield stress value of nc nickel was obtained at a temperature of 673 K as a result of its thermodynamic instability.