Effect of Ni Enrichment on the Microstructure, Mechanical, and Tribological Properties of Hydrophobic Ni₃Al Alloy Coatings

Ni₃Al and Ni-rich Ni₃Al coatings were deposited over SS-304 substrate using DC magnetron sputtering and co-sputtering at ambient temperature. The concentration of Ni was varied by altering the sputtering power to the Ni target during the co-sputtering process. The evolution of phase, microstructure, and surface topography was investigated using, GIXRD, FESEM, and AFM, respectively, whereas the hardness, wear, and electrochemical properties were investigated using nanoindentation, ball-on-disk tribometer, and electrochemical impedance spectroscope, respectively. The results of the XRD spectra showed that the intensity of Ni₃Al (111) and (220) increases with an increase in Ni concentration. The results of mechanical and tribological properties show that the hardness, Young’s modulus, wear, and corrosion-resistant properties of the coatings decrease with the continuous and simultaneous increase in the Ni concentration and testing temperature. However, the contact angle measurements proclaimed that the Ni₃Al film becomes hydrophobic when the concentration of Ni was increased in the Ni₃Al matrix. The maximum hardness, Young’s modulus, and contact angle of (13.25 ± 0.75) GPa, (231 ± 16) GPa, and 117° were shown by Ni₃Al at ambient temperature.