Spectroscopic evaluation of nitrogen glow discharge for the surface nitriding of Ti-6Al-4V alloy

Abstract

The study investigates the spectral characteristics of a DC glow discharge generated in a parallel electrode configuration for nitriding the Ti-6Al-4V alloy to enhance its surface properties. At first, optical emission spectroscopy (OES) was used to optimize the glow discharge for a certain nitrogen fill pressure and discharge power. The Ti-6Al-4V alloy is then subjected to plasma treatment in an optimized N2-discharge environment. The treated samples' microstructures, surface morphology, elemental composition, and surface roughness are all determined by several material characterization techniques, including XRD, SEM, EDX, and AFM. The Ti-alloy's crystalline phase distribution affects the alloy's physical and chemical characteristics, which determine its suitability for various applications in aerospace and medical implants. A phase shift from Ti(101)α to Ti(110)β is observed owing to the progressive increase in nitrogen interstitials in Ti sites, which promotes the phase transition. The EDX results show that the amount of nitrogen in the spectrum increases, demonstrating that nitrogen has successfully been incorporated into the surfaces of alloys. The surface morphology of the treated samples has improved with longer treatment times, as seen by SEM pictures of samples that have received plasma treatment. Finally, the comparison of the samples' AFM topological measurements and textures at 5, 10, and 15 h demonstrates the importance of treatment time on the development of the Ti-6Al-4V surface roughness and microstructure.