Origin of grey spots on the surface of metallic glasses under Ar+ ion irradiation: The surface and volume properties

The nature of grey spots on the surface of amorphous Fe67Cr18B15 metglass ribbons irradiated by 30 keV Ar+ ions is investigated. Changes in the surface and volume properties of samples are analyzed bearing in mind the presence of competitive processes of ordering and disordering in the structure under irradiation at initial stage of crystallization (T = 500 °C). Changes in the volume properties of the samples become apparent in their structure, electrical and magnetic properties and are caused by radiation-enhanced diffusion at high gradients in the concentration of defects generated by Ar+ irradiation. It is established that grey spots are shown by decrease in the reflection coefficient in a visible range. They emerge as a result of reorganization in the electronic structure of irradiated ribbons due to damage in the short-range order and formation of non-uniformly scaled atomic structure during transition from the medium-range to the long-range atomic order. Experimental data are in accord with the calculations in the framework of the free electrons model.