Chemical vapor deposition of TiN on a CoCrFeNi multi-principal element alloy substrate

SURFACE & COATINGS TECHNOLOGY

卷:393

Article

Boor, Katalin¹  Qiu, Ren²  Forslund, Axel³  Backe, Olof²  Larsson, Henrik³  Lindahl, Erik⁴  Halvarsson, Mats²  Boman, Mats¹  von Fieandt, Linus⁴ 

[1] Uppsala Univ, Dept Chem, SE-5120 Uppsala, Sweden

[2] Chalmers Univ Technol, Dept Phys, SE-41296 Gothenburg, Sweden

[3] Royal Inst Technol, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden

[4] AB Sandvik Coromant, SE-12679 Hagersten, Sweden

关键词: Chemical vapor deposition;    Transmission electron microscopy;    X-ray diffraction;    Calphad;    Titanium nitride;    Multi-principal element alloy;   

DOI  :  10.1016/j.surfcoat.2020.125778

来源: Elsevier

【 摘 要 】

The reactivity of a quaternary multi-principal element alloy (MPEA), CoCrFeNi, as a substrate in thermal halide chemical vapor deposition (CVD) processes for titanium nitride (TiN) coatings was studied. The coatings were deposited at 850 degrees C-950 degrees C using TiCl4, H-2 and N-2 precursors. The coating microstructures were characterized using X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM/TEM) with energy dispersive X-ray spectroscopy (EDS). Thermodynamic calculations of substrate and coating stability for a gas phase environment of N-2 and H-2 within a temperature range relevant for the experiments showed that Cr is expected to form hexagonal Cr2N and cubic (Ti1-epsilon 1 Cr epsilon 1)N or (Cr1-epsilon 2 Ti epsilon 2)N phases. These phases could however not be discerned in the samples by XRD after the depositions. Cr was detected at the grain boundaries and the top surface by EDS for a sample synthesized at 950 degrees C. Grain boundary and surface diffusion, respectively, were the suggested mechanisms for Cr transport into the coating and onto the top surface. Although thermodynamic calculations indicated that Cr is the most easily etched component of the CoCrFeNi alloy to form gaseous chlorides in similar concentrations to that of the residual Ti-chlorides, no sign of etching were found according to the imaging of the sample cross-sections using SEM and TEM. Cross-section and top surface images further confirmed that the choice of substrate had no significant detrimental influence on the film growth or microstructure.

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