Mechanical properties of sputtered Cu/V and Al/Nb multilayer films

We have investigated the microstructure and mechanical properties of sputter-deposited Cu/V and Al/Nb metallic multilayer systems in this study and compared their mechanical properties to Cu/Cr and Cu/Nb reported earlier. These multilayer films are all of fcc/bcc type, with Kurdjumov-Sachs orientation relationship: {111}fcc//{110}bcc; < 110 > fcc//< 111 > bcc. In all cases, hardnesses of multilayers increase with decreasing layer thickness, and reach maxima at approximately 2-5 nm layer thickness. The differences in their mechanical properties (the Hall-Petch slope and peak hardness) are interpreted in terms of their differences in shear moduli, heat of mixing, and characteristics of interfaces. (C) 2007 Elsevier B.V. All rights reserved.