High-Throughput First-Principles Search for Ceramic Superlattices with Improved Ductility and Fracture Resistance
19 Pages Posted: 5 Oct 2020 Publication Status: Accepted
Superlattices—alternating coherently grown materials of nm thicknesses—proved their potential for enhancing typically antagonistic properties of ceramics: ductility, hardness, and fracture toughness. Material selection, however, is far from trivial, as superlattice films do not simply combine mechanical properties of their layer components. Here we employ high-throughput density functional theory calculations to develop design guidelines for nanolaminates combining cubic transition metal nitride and/or carbide ceramics. Out of 153 MX/M*X* superlattices (M = Al, Ti, Zr, Hf, Nb, V, Ta, Mo, W, and X = C, N) 145 are chemically and mechanically stable and most often contain vacancies on the non-metallic sublattice. Superior ductility together with moderate-to-high fracture toughness and interface strength (above that of the cubic TiN) narrow the set of perspective candidates. Key ingredients promoting the interface-induced enhancement of hardness and/or fracture toughness are lattices parameter and shear modulus mismatch of the layer components. Adding the requirement of phonon stability yields MoN/TaN; WN/TiN; VC/TaN; NbC/M*N, M* = Mo, W; TaC/M*N, M* = Mo, W; MoC/TaN; and WC/X*N, M* = Nb, Ta; as the top aspirants for novel superlattice films.
Keywords: Ab initio calculations, Superlattice, Ductility, Toughness, High-throughput screening
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