Effect of superlattice layer elastic moduli on hardness

Abstract
Epitaxial V0.6Nb0.4N/NbN superlattices have been deposited on MgO(100) by reactive magnetron sputtering. The V0.6Nb0.4N alloy was chosen for one layer, rather than VN, in order to reduce the lattice mismatch from 5.7% to 3.5%, allowing growth of superlattices with relatively planar layers. The elastic moduli of NbN and V0.6Nb0.4N are nearly equal, in contrast to previously studied high‐hardness nitride superlattices where the layer moduli differed substantially. Vickers microhardness measurements showed no measurable deviation (<4 GPa) from alloy values. The results verify that the difference in layer elastic moduli is the primary parameter determining nitride superlattice hardening.