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 diffractometr y (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron micr oscopy (TEM) and a hardness tester were used to understand the microstructu re 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 envi ronment with a spinning beam. The results show that the solidified melt con sists of alpha ' -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 har dness of between 500 and 800 HV. (C) 2001 Elsevier Science B.V. All rights reserved.