Investigation of nitrogen diffusion during laser heating of titanium

Abstract

Titanium alloys find wide application in industry despite their poor wear resistance. One of the alternative methods to improve the surface properties of titanium alloys is the laser gas alloying process. The modelling of the laser assisted nitrogen diffusion process minimises experimental costs and gives insight into the diffusion process. In the present study, nitrogen diffusion into titanium as a result of laser heating is considered. A transient heat transfer analysis based on the Fourier theory is carried out and a closed form solution taking into account the phase change process is introduced. The diffusion coefficient obtained from a previous study is employed when computing the nitrogen concentration inside the substrate. In order to investigate the effect of laser parameters on the diffusion process five pulse lengths with the same energy content are considered. It is found that the influence of the pulse length on the nitrogen concentration is considerable and its effect on the diffusion coefficient is significant.