Nanoindentation and microstructural studies of Al/TiN multilayers with unequal volume fractions

The mechanical behavior of nanoscale Al/TiN multilayers with a thickness ratio of 9:1 deposited by reactive sputter deposition, with TiN layer thicknesses of 1-50 nm, has been evaluated. Hardness values measured by nanoindentation methods showed considerably higher hardness than a rule of mixtures estimate, and increasing hardness with decreasing layer thickness. Microstructural analysis has been performed using transmission electron microscopy (TEM) and high-resolution TEM. A dislocation image force model is used to understand the strengthening mechanisms. (c) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.