Skip to Main Content
Your organization might have access to this article on the publisher's site. To check, click on this link:http://dx.doi.org/+10.1063/1.2885090
The indentation depth effect has been systematically examined on the mechanical properties of electrodeposited nickel films under 0% and 10% tensile strains. It is found that the indentation depth is proportional to the square root of the loads applied and the depth profiles of hardness and elastic modulus follow the similar trend of change with maximal values at the surface skins. The hardness and modulus then attenuate to a value of about half of the maximum, which follows the model proposed by Graca etal, Surf. Coat. Technol. (in press) with the mechanism of geometrically necessary dislocations and surface free energy. We suggest that the effect of surface oxidation and surface bond contraction [C. Q. Sun, Prog. Solid State Chem. 35, 1 (2007)] contributes intrinsically to the anomalous skin strengthening because of the local strain and energy trapping caused by surface bonds breaking.