Study of the surface layer formed by the laser processing of Ti–6Al–4V alloy in a dilute nitrogen environment

Optical microscopy, scanning electron microscopy (SEM), X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and a hardness tester were used to understand the microstructure and to characterise the phases formed in a Ti–6Al–4V alloy at different tracks and depths, produced by laser nitriding under a dilute nitrogen environment with a spinning beam. The results show that the solidified melt consists of α′-Ti and TiNx. Using XRD, x was determined to be 0.75 while from XPS, x lay in a range of 0.5–0.8. The melt zone showed a range of hardness of between 500 and 800 HV.