TiN/TaN超晶格中界面调控的缺陷工程以提升硬度与断裂韧性
Interface-Controlled Defect Engineering in TiN/TaN Superlattices for Enhanced Hardness and Fracture Toughness
AI总结：
该研究通过在TiN/TaN超晶格界面掺杂C、B、Si调控缺陷，使硬度最高达41 GPa、断裂韧性最高达4.0 MPam^0.5，为陶瓷氮化物超晶格力学性能调控提供了界面化学设计新参数。
AI中文摘要：
本研究设计了TiN/TaN超晶格涂层，以探究原子级界面化学与缺陷稳定化TaN层如何调控硬度和断裂韧性。基于第一性原理预测（该预测确定TaN基层比TiN更耐损伤），通过反应磁控溅射合成了 bilayer周期为6 nm的相干超晶格，并在界面处掺杂C、B或Si。结构与化学分析显示，样品具有相干面心立方（fcc）结构，界面清晰明确；Si优先偏聚于界面，同时融入TiN和TaN，而C和B则主要扩散进入TaN层，改变了共格应变、键合状态和缺陷数量。结果表明，未掺杂超晶格的硬度为34 GPa，Si掺杂结构的硬度提升至41 GPa；未掺杂超晶格的断裂韧性为2.8 MPam^0.5，B掺杂超晶格的断裂韧性提升至4.0 MPam^0.5。第一性原理计算显示，空位稳定化的Ta_xN_y增强了弹性顺应性和弹性对比度，而非本征韧性；B诱导的额外增韧表明，在化学工程化界面处存在局部缺陷辅助的能量耗散。因此，Si可最大化界面强化效果，而B在保持高硬度（38 GPa）的同时，提供了最佳的硬度-韧性平衡。这些发现确立了界面化学作为调控陶瓷氮化物超晶格力学性能的额外设计参数。
英文摘要：
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.
