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: {1 1 1}fcc//{1 1 0}bcc; 〈1 1 0〉fcc//〈1 1 1〉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.