Interface-Controlled Defect Engineering in TiN/TaN Superlattices for Enhanced Hardness and Fracture Toughness
Abstract
TiNTaN superlattice coatings were designed to investigate how atomic-scale interface chemistry and defect-stabilized TaN layers govern hardness and fracture toughness. Guided by first-principles predictions identifying TaN-based layers as more damage tolerant than TiN, coherent superlattices with a bilayer period of 6 nm were synthesized by reactive magnetron sputtering and interfacially doped with C, B, or Si. Structural and chemical analyses reveal coherent fcc architectures with well-defined interfaces. Si segregates preferentially to the interfaces while incorporating into both TiN and TaN, whereas C and B predominantly diffuse into the TaN layers, modifying coherency strain, bonding, and defect populations. Consequently, hardness increases from 34 GPa for the undoped superlattice to 41 GPa for the Si-doped architecture, whereas fracture toughness increases from 2.8 to 4.0 MPam0.5 for the B-doped superlattice. First-principles calculations show that vacancy-stabilized TaxNy enhances elastic compliance and elastic contrast rather than intrinsic toughness, while the additional toughening induced by B indicates localized defect-assisted energy dissipation at chemically engineered interfaces. Thus, Si maximizes interface strengthening, whereas B provides the most favourable hardness-toughness balance while preserving high hardness, 38 GPa. These findings establish interface chemistry as an additional design parameter for tailoring the mechanical performance of ceramic nitride superlattices.
Versions
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BibTeX
@misc{gaoa2026interfacecontrolled,
title = {{Interface-Controlled Defect Engineering in TiN/TaN Superlattices for Enhanced Hardness and Fracture Toughness}},
author = {Zecui Gaoa and Qimin Wang and Julian Buchinger and Nikola Koutna and Marcus Hans and Zaoli Zhang and Jochen Schneider and Daniel Primetzhofer and Paul Heinz Mayrhofer},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2608.24607},
eprint = {2608.24607},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.24607},
}
RIS
TY - UNPB
TI - Interface-Controlled Defect Engineering in TiN/TaN Superlattices for Enhanced Hardness and Fracture Toughness
AU - Zecui Gaoa
AU - Qimin Wang
AU - Julian Buchinger
AU - Nikola Koutna
AU - Marcus Hans
AU - Zaoli Zhang
AU - Jochen Schneider
AU - Daniel Primetzhofer
AU - Paul Heinz Mayrhofer
PY - 2026
DA - 2026/08/25
PB - arXiv
DO - 10.48550/arxiv.2608.24607
UR - https://arxiv.org/abs/2608.24607
AB - TiNTaN superlattice coatings were designed to investigate how atomic-scale interface chemistry and defect-stabilized TaN layers govern hardness and fracture toughness. Guided by first-principles predictions identifying TaN-based layers as more damage tolerant than TiN, coherent superlattices with a bilayer period of 6 nm were synthesized by reactive magnetron sputtering and interfacially doped with C, B, or Si. Structural and chemical analyses reveal coherent fcc architectures with well-defined interfaces. Si segregates preferentially to the interfaces while incorporating into both TiN and TaN, whereas C and B predominantly diffuse into the TaN layers, modifying coherency strain, bonding, and defect populations. Consequently, hardness increases from 34 GPa for the undoped superlattice to 41 GPa for the Si-doped architecture, whereas fracture toughness increases from 2.8 to 4.0 MPam0.5 for the B-doped superlattice. First-principles calculations show that vacancy-stabilized TaxNy enhances elastic compliance and elastic contrast rather than intrinsic toughness, while the additional toughening induced by B indicates localized defect-assisted energy dissipation at chemically engineered interfaces. Thus, Si maximizes interface strengthening, whereas B provides the most favourable hardness-toughness balance while preserving high hardness, 38 GPa. These findings establish interface chemistry as an additional design parameter for tailoring the mechanical performance of ceramic nitride superlattices.
ER -