Helium ions irradiation-induced surface damage in Fe-based melt-spun ribbons

The Fe78Si8B14 and Fe78P8B14 ribbons with different wheel speeds were prepared by melt-spinning, and their responses to He+ ion irradiation were investigated. Previous studies had shown that the ion beam resistance capability of amorphous ribbons was better than their corresponding crystalline counterparts. However, no significant changes on the surface at low fluence are observed. At a relatively higher fluence, both the ribbons prepared at low and high wheel speeds behave the similar irradiation responses: peeling, flaking and multi-layer damages occur. The fully amorphous ribbons prepared at a high wheel speed can accommodate partial incident ions owing to the inherent disordered structure. As the irradiation fluence increases, they fail to accommodate the excess incident ions, which easily aggregate to result in the surface damage. While the partial amorphous ribbons prepared at a low wheel speed possess lots of unstable crystalline grain boundaries owing to the precipitation of Si- or P-rich phase, which may act as the source for the irradiation-induced defects annihilation. Results show that the size and the fraction of precipitate phases in amorphous matrix may play a dominated role in resisting the ion irradiation.