Modelling of direct FEL synthesis of textured TiN coatings on titanium

Abstract

Surface treatment by means of pulsed laser beams in reactive atmospheres is an attractive technique to enhance the surface features, such as corrosion and wear resistance or hardness. Among all laser types, the free electron laser (FEL) is relatively new for materials processing, its main peculiarities being the high power, pulse structure, high repetition rates and macropulse forming. So the FEL has the ability to significantly improve processing speed and versatility of laser material treatments. We have employed the 1.7 kW FEL at the Jefferson Lab (Virginia, USA) to irradiate pure titanium substrates in nitrogen atmosphere. We have investigated the influence of various experimental parameters (macropulse duration, macropulse repetition rate, spot overlap and laser fluence) on the nitrogen incorporation and the resulting microstructures