Synthesis and DFT calculations of high entropy six-component Ti-based MAX of (Ti, M)2AlC (M=Zr, Nb, Ta, Mo, W)

IF 3.8 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum Pub Date : 2025-04-15 DOI:10.1016/j.vacuum.2025.114332

Jun Ji , Xinyu Zhan , Xiaoman Jiang , Yongji Wang , Mingling Li , Huamin Gao , Bensong Chen , Dechun Li

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引用次数: 0

Abstract

High-entropy six-component Ti-based MAX phase (Ti_0.5Nb_0.15Zr_0.1Mo_0.1Ta_0.1W_0.05)₂AlC was synthesized via molten salt shielding synthesis (MS³), demonstrating exceptional chemical stability against corrosive etching. Transmission electron microscopy (TEM) with energy-dispersive spectroscopy (EDS) confirmed homogeneous elemental distribution and expanded (004) interplanar spacing (0.352 nm vs. 0.331 nm in Ti₂AlC), consistent with density functional theory (DFT) calculations. The stability enhancement mechanism was investigated through electronic structure analysis and defect dynamics. DFT calculations revealed that high-entropy doping at M-sites strengthens M − Al bonds via hybridization between transition metal d-orbitals (Nb/Zr/Mo-4d, Ta/W-5d) and C/Al orbitals, increasing Al vacancy formation energy from 2.26 eV (Ti₂AlC) to 2.83 eV (HE-MAX). Additionally, Al vacancy migration energy surged to 1.07 eV, 39 % higher than Ti₂AlC (0.77 eV), effectively suppressing defect-mediated degradation. These dual mechanisms underpin the remarkable resistance of HE-MAX to HF/NaF-HCl etching, offering insights for designing stable MAX phases for extreme environments.

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(Ti, M)2AlC (M=Zr, Nb, Ta, Mo, W) 的高熵六组分 Ti 基 MAX 的合成与 DFT 计算

采用熔盐屏蔽法（MS3）合成了高熵六组分ti基MAX相（Ti0.5Nb0.15Zr0.1Mo0.1Ta0.1W0.05）2AlC，该相具有优异的抗腐蚀化学稳定性。透射电子显微镜（TEM）和能谱分析（EDS）证实了Ti2AlC元素的均匀分布和扩大的（004）面间距（0.352 nm比0.331 nm），与密度泛函理论（DFT）计算一致。通过电子结构分析和缺陷动力学研究了其稳定性增强机理。DFT计算表明，M位的高熵掺杂通过过渡金属d轨道（Nb/Zr/Mo-4d, Ta/W-5d）和C/Al轨道之间的杂化强化了M- Al键，将Al空位形成能从2.26 eV （Ti2AlC）提高到2.83 eV （HE-MAX）。Al空位迁移能达到1.07 eV，比Ti2AlC （0.77 eV）高39%，有效抑制了缺陷介导的降解。这些双重机制支撑了HE-MAX对HF/NaF-HCl蚀刻的卓越抗性，为极端环境下设计稳定的MAX相位提供了见解。

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来源期刊

Vacuum 工程技术-材料科学：综合

CiteScore

6.80

自引率

17.50%

发文量

审稿时长

34 days

期刊介绍： Vacuum is an international rapid publications journal with a focus on short communication. All papers are peer-reviewed, with the review process for short communication geared towards very fast turnaround times. The journal also published full research papers, thematic issues and selected papers from leading conferences. A report in Vacuum should represent a major advance in an area that involves a controlled environment at pressures of one atmosphere or below. The scope of the journal includes: 1. Vacuum; original developments in vacuum pumping and instrumentation, vacuum measurement, vacuum gas dynamics, gas-surface interactions, surface treatment for UHV applications and low outgassing, vacuum melting, sintering, and vacuum metrology. Technology and solutions for large-scale facilities (e.g., particle accelerators and fusion devices). New instrumentation ( e.g., detectors and electron microscopes). 2. Plasma science; advances in PVD, CVD, plasma-assisted CVD, ion sources, deposition processes and analysis. 3. Surface science; surface engineering, surface chemistry, surface analysis, crystal growth, ion-surface interactions and etching, nanometer-scale processing, surface modification. 4. Materials science; novel functional or structural materials. Metals, ceramics, and polymers. Experiments, simulations, and modelling for understanding structure-property relationships. Thin films and coatings. Nanostructures and ion implantation.