Influence of film thickness on the structural transition cubic/hexagonal within Ti0.38Al0.62N films

THIN SOLID FILMS

卷:649

Article

Pinot, Y.¹  Tuilier, M. -H.¹  Pac, M. -J.¹  Rousselot, C.²  Thiaudiere, D.³  Ulhaq-Bouillet, C.⁴ 

[1] Univ Haute Alsace, Lab Phys & Mecan Text EA 4365, F-68093 Mulhouse, France

[2] Univ Bourgogne Franche Comte, FEMTO ST UMR CNRS 6174, BP 71427, F-25211 Montbeliard, France

[3] Synchrotron Soleil, F-91192 Gif Sur Yvette, France

[4] Univ Strasbourg, Inst Phys & Chim Mat Strasbourg, UMR CNRS 7504, F-67087 Strasbourg, France

关键词: Metallic nitride coatings;    Crystal growth;    XRD;    TEM;    XAFS;    Diffraction anomalous fine structure;   

DOI  :  10.1016/j.tsf.2018.01.024

来源: Elsevier

【 摘 要 】

Metastable Ti1-xAlxN films have the more outstanding functional properties in the range of composition around x = 0.6 for their use as protective coatings. They exhibit complex texture because of the phase transition between TiN-like rocksalt and AlN-like wurtzite structures. The competitive growth between cubic and wurtzite domains is studied in metastable Ti0.38Al0.62N thin film deposited by reactive magnetron sputtering for thicknesses between 1 and 3.7 mu m. Long-range order is analysed within the film by X-ray diffraction and cross-sectional TEM imaging. The study is complemented by using Ti K-edge diffraction anomalous spectroscopy to obtain differentiated information on short-range order around Ti atoms incorporated in cubic and wurtzite domains. The growth along the [111]c direction has the effect of promoting the appearance of crystallites with wurtzite symmetry oriented along [001]h. In the middle of the layer, cubic and wurtzite domains become coherently oriented. Lattice distortions, which affect long- and short-range order, are revealed by the anisotropy of broadening of the diffraction lines and by spectroscopic data collected on the main diffraction lines. The fine preedge structure indicates a strong distortion of the tetrahedral sites occupied by Ti atoms along the c axis, which minimizes the in-plane lattice mismatch. Near the film surface, a dramatic change in growth directions is observed. A better understanding of the structural transition mechanism in the (Ti,Al)N system could help improve the mechanical performances of these coatings in the future.

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