Influence of carbon deficiency on phase formation and thermal stability of super-hard TaCy thin films

Synthesis and characterization of multicomponent (CrNbTaTiW)C films for increased hardness and corrosion resistance

“…A transition metal carbide with a B1 (NaCl) structure can be described as an fcc (face centred cubic) lattice of metal atoms with carbon in the octahedral sites. Carbides usually exhibit a mixture of metallic, covalent and ionic bonding [20][21][22][23] and the use of the metallic radius in 12-coordination to calculate lattice distortion is therefore questionable. However, to estimate trends regarding the distortion of the metal fcc lattice we can apply Eq.…”

Sub-stoichiometry-facilitated oxidation kinetics in a δ-TixC-doped Ti-based alloy

“…4,5 An abundance of experimental and theoretical efforts have evidenced the linkage between vacancy concentration and fluctuations in bulk properties such as hardness, chemical stability, and electric conductivity. 4,[6][7][8] Recent literature also reflects attempts to construct the phase equilibrium framework via ab initio simulation. 9,10 Amongst these group IV-V metal carbides, more attention has been directed to titanium carbide, namely, the δ-Ti x C phase.…”

Tuning structure and mechanical properties of Ta-C coatings by N-alloying and vacancy population

“…Transition metal (TM) carbides and nitrides belong to the class of ultra-high temperature ceramics (UHTC) exhibiting highly interesting properties. Various members of this materials family present a unique mix of high hardness 1 , high thermal and chemical stability 2 , accompanied by electrical resistivity that is comparable to their pure transition metals 3 (e.g. Ta-C 25 µΩ cm) 4 .…”

“…diffusion barriers or piezo-electric applications) gained a lot of scientific and industrial attention for nitride-based systems containing Ti and/or Al 5 . Among the TM carbides, Ta-C prevail the highest melting temperature of all known binary systems (3983 °C) 6 and in relation to the predominant covalent-metallic bonding character extreme hardness and chemical inertness 1 , 7 . However, for a broad utilization of Ta-C based materials – either as structural components or thin films – the tremendously low ductility and extremely high transition temperature, where macroscopic ductile behavior is observed (about 0.5·T m ) 8 , are major limiting issues.…”

“…This has recently been verified through detailed ab initio calculations, showing that depending on the vacancy type (metallic or non-metallic sublattice) and content, δ-TaN can be stabilized over π-TaN even at 0 K 21 . For Ta-C, non-metallic vacancies are more decisive than metal vacancies for promoting a stabilization of the cubic structure, whereas for Ta-N, metallic vacancies are of crucial importance 1 , 22 . In general, the vacancy stabilized structures may also influence the hardness, especially when thereby the valence electron concentrations (VEC) is tuned towards 8.4 e/f.u.…”