Correlation of Microstructural and Mechanical Properties of CVD Deposited TiAlN Coatings

Titanium aluminum nitride (TiAlN) thin films were synthesized with different N₂ flow rate on p-type Si (100) substrate and characterized by FESEM, AFM, XRD and nanoindentation to investigate the morphology, structural and mechanical properties. The FESEM images revealed non-uniform grain distribution with a higher degree of pores with the increase in N₂ flow rate. The XRD data indicated the presence of AlN, TiAlN, Al₂O₃ dominant phases at 33.07°, 55.5°, 61.79° and 47.84°, 54.67° diffraction angles attributed to (100), (220) and (400), (112) diffraction plane, respectively. The AFM images revealed the average roughness as 36.9 nm for 30 sccm N₂ flow rate. Furthermore, the mechanical properties such as H, E, plasticity index (H/E) and deformation to plastic resistance (H³/E²) of TiAlN thin film were found to be 21 GPa, 400 GPa, 0.094 and 0.318 GPa, respectively, indicating higher resistance to crack with increasing N₂ flow rate.