Development of VC-based Early Transition Metal Carbide Superlattices via Compound Target Magnetron Sputtering

Abstract

Transition metal carbides are known to feature high thermal and mechanic stability as well as high melting points, sometimes above 4000 °C, and can be regarded as ultra-high temperature ceramics (UHTC). The huge downsides to those materials is the high inherent brittleness. Superlattice architecture describes the alternation of coherently grown nanolayers of two or more materials. By creating such superlattices, optical, magnetic, electronic, tribological, or mechanical properties can be influenced. The hardness but also the toughness of superlattice materials can be significantly higher than their monolithically grown components. Therefore, we developed superlattice structures of selected transition metal carbides combined with VC as well as performed bilayer period variations between 2 and 50 nm. The selected carbide combinations are based on density functional theory simulations, which revealed VC containing films as most promising candidates to have an improved toughness behavior due to the superlattice structure. All coatings are developed via DC magnetron sputtering using the respective ceramic targets. Their characterization includes X-ray diffraction, scanning and transmission electron microscopy, energy dispersive X-ray spectroscopy, elastic recoil detection analysis, nanoindentation and in-situ micromechanical investigations.