Ion-beam assisted deposition effect on residual stresses in 304L stainless steel films

Improvement of the tribological behaviour of bulk material with a deposited coating on its surface is widely used because it generally provides good results. Nevertheless, the deposition process is often responsible of residual stress generation in the film which may then lead to a degradation of the coated sample. The aim of this work is to show that high compressive stresses existing in a 304L Stainless Steel sputter-deposited coating may be reduced when using ion irradiation during thin film growth. The evolution of the mechanical and microstructural state as a function of ion irradiation have been studied by X-ray diffraction and curvature methods. The results indicate a large decrease of the compressive stress magnitude (about 50%) and an increase of the size of coherently diffracting domains (factor 10) for ion-beam assisted deposition process with respect to the classical one. Furthermore, we observed a large difference (around 1 GPa) for all the samples between the stress level determined by X-ray diffraction and the one related to curvature method. In addition, conversion electron Mossbauer spectroscopy results are closely correlated to the X-ray diffraction ones.