Single-crystal TiN/V0.6Nb0.4N superlattice films were deposited on MgO(100) substrates using ultrahigh vacuum reactive sputtering from two magnetron sources with a computer-controlled shutter. X-ray diffractometer measurements showed first- and second-order superlattice peaks while electron diffraction showed up to seventh-order superlattice reflections. Direct observations using cross-sectional transmission electron microscopy showed that the superlattices had flat, abrupt interfaces, but contained threading dislocations. Microhardness values for the superlattices ranged from to 3100 to 4100 kg/mm2, depending on the superlattice period (λ), compared with 1500 for an alloy with equal average composition. The hardness values for these lattice-matched superlattices agreed with those previously reported for TiN/VN superlattices with a lattice mismatch of 2.4%, although the hardness peak was less pronounced. The present results indicate that coherency strains do not play the major role in enhancing the hardness of these nitride superlattices.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)