High quality Hastelloy films deposited by XeCl pulsed laser ablation

Abstract

Pulsed laser ablation has been used to deposit Hastelloy thin films on carbon steel substrates at room temperature. Depositions have been carried out by XeCl excimer laser ablation ( λ=308 nm, τ=30 ns) of a bulk Hastelloy target in a high vacuum system ( p=10 −5 Pa). In order to obtain as thick and uniform films as possible, we took in account the maximum plume deflection angle we observed in our experiments. Optical studies of the plume revealed a deviation of about 15° towards the laser beam. To minimize the effects of the plume deflection, the substrate was placed along the deflected plume axis instead of the normal to the target surface. The plume deflection angle and the ablation rate of Hastelloy target as a function of number of laser pulses per site have been also measured. Scanning electron microscopy (SEM), energy dispersion X-ray (EDX) spectroscopy and X-ray diffraction (XRD) have been performed to analyse, respectively, the surface morphology, the chemical composition and the crystallographic structure of the deposited films. In order to correlate the microstructure of the film surface with its corrosion properties, potentiodynamic curves and linear polarisation resistance analyses have been carried out.