Architecture-driven deformation and fracture behavior of nanolamellar TiN/Nb coatings

Abstract

Despite extensive studies on ceramic multilayers, combinations of nitrides with metals remain underexplored, particularly in the context of enhancing fracture resistance through interface design. In this study, we explore the mechanical and thermodynamic properties of 30 multilayered systems combining nitrides (XN) and carbides (XC) of group IV transition metals, X = {Ti, Zr, Hf}, with group V–VI high-temperature metals, M = {V, Nb, Ta, Mo, W}, using Density Functional Theory. Among them, TiN/Nb and TiN/V emerge as promising candidates based on formation energies, high interface strengths, and favorable elastic contrasts. Focusing on TiN/Nb—due to superior oxidation resistance—we fabricate multilayers via non-reactive sputtering and confirm the formation of distinct TiN and Nb layers. Compression tests on FIB-milled micropillars reveal that the deformation behavior is governed by bilayer period (Λ) and TiN:Nb layer-thickness ratio (Γ). Systems with lower Γ exhibit increased compressive strain-to-failure, while those with higher TiN content (Γ = 6) show a more brittle-like fracture. The observed plasticity aligns with confined layer slip (CLS) behavior, where dislocation motion is restricted to the metallic Nb layers. These findings demonstrate that TiN/Nb multilayers can be tailored for improved toughness and ductility, offering a pathway towards advanced coatings for extreme environments.