Numerical Simulation of the heat affected zone of nickel ablated with femtosecond laser

In order to quantify the heat affected zone(HAZ) of femtosecond machining.Based on a two-dimensional model of the two temperature model(TTM),the radial heat affected zone of femtosecond laser ablation on nickel was simulated numerically with finite-difference method.The radial HAZ was defined as two parts,one was the melting and resolidification zone(between melting temperature and phase explosion temperature) and the other was thermal activation zone(between thermal activation temperature and melting temperature).The evolution of the temperature as a function of time was studied,leading to a radial HAZ width of 160nm for 500nm thick Ni samples,which showed that the heat affected zone of femtosecond machining is very small.Besides,the effects of the thermal conductivity and the specific heat of the electron on the radial HAZ were analyzed.