Surface vitrification of iron and FeCuNbSiB alloy irradiated by intense pulsed ion beam

Abstract

Intense pulsed ion beam (IPIB) is an emerging flash heat source for surface modification of metal. In IPIB treatment, the formation of amorphous phase is always considered as a significant mechanism to modify and improve the surface properties of target, due to the excellent mechanical performance of amorphous alloy. Thus, the understanding of surface vitrification process and its conditions induced by IPIB irradiation is of great value for its application. In this work, pure iron and FeCuNbSiB alloy were chosen as target for investigation in term of the difference of their glass forming ability (GFA). XRD results showed that the measurable amorphous layer cannot be formed in the surface of both of these two alloys after IPIB irradiation. Thermal field and solute diffusion were studied using the finite element method. It is indicated that during the IPIB irradiation, the molten surface layer of FeCuNbSiB alloy is heterogeneous, and thus it has much lower GFA than the Fe-Cu-Nb-Si-B mixed system. It is proposed that the sufficient mixture of elements in the molten surface layer is indispensable for surface vitrification. In addition, the formation of craters and cracks on the surface will be harmful to form amorphous layer.