Desorption of Al and Phase Transformation of Ti2AlN MAX Thin Film upon Annealing in Ultra-High-Vacuum
Desorption of Al and Phase Transformation of Ti2AlN MAX Thin Film upon Annealing in Ultra-High-Vacuum
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DOI：
10.1021/jp505428a
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发表时间：
2014-08
影响因子：
3.7
通讯作者：
Zheng Zhang;Hongmei Jin;J. Chai;Lu Shen;H. L. Seng;Jisheng Pan;L. Wong;M. Sullivan;Shijie Wang
中科院分区：
文献类型：
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作者：
Zheng Zhang;Hongmei Jin;J. Chai;Lu Shen;H. L. Seng;Jisheng Pan;L. Wong;M. Sullivan;Shijie Wang
采用X射线光电子能谱（XPS）和原子力显微镜（AFM）、二次离子质谱（SIMS）、能量色散X射线谱（EDS）、X射线衍射（XRD）和纳米压痕（NMD）等技术，原位研究了单晶Ti 2AlN薄膜在超高真空中的相稳定性. Ti 2AlN在高达600 °C的温度下稳定。在700 °C下，Al优先从表面脱附，并且通过XPS在900 °C下变得几乎检测不到，其中具有平台形态的单晶Ti 2AlN转变为多晶δ-TiN 1-x和α-TiN0.75-y相，表面上存在空隙并且膜厚度减小。还观察到包括硬度和杨氏模量的机械性能已经劣化。密度泛函理论计算表明，Al原子优先沿沿着Al基面水平扩散。铝的高蒸气压使其从表面脱附，导致铝组分减少，表面形成空洞，从而导致铝的析出。
Phase stability of single-crystalline Ti2AlN thin film in ultra-high vacuum has been studied in situ by X-ray photoelectron spectroscopy as a function of annealing temperature and ex situ by atomic force microscopy, secondary ion mass spectroscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and nanoindentation. Ti2AlN is stable up to 600 °C. At 700 °C, Al is preferentially desorbed from the surface and becomes nearly undetected at 900 °C by XPS, where single-crystalline Ti2AlN with terrace morphology transforms into polycrystalline δ-TiN1–x and ξ-TiN0.75–y phases with voids on the surface and reduced film thickness. Mechanical properties including hardness and Young’s modulus are also observed to have deteriorated. Density functional theory calculation shows that Al atoms prefer to diffuse out from the Ti2AlN horizontally along the Al basal planes. The subsequent desorption of Al from surface due to its high vapor pressure results in the decreased Al composition, the void formation on the su...