Structural modifications of swift-ion-bombarded metallic glasses studied by high-energy X-ray synchrotron radiation

Modifications of structural arrangements including relaxation processes were investigated in swift-heavy-ion-bombarded Fe73Cu1Nb3Si16B7 metallic glass. The irradiation of as-quenched amorphous ribbons was accomplished with 3MeVu-1 (u is atomic mass unit) and 11.1MeVu-1 Au ions with total fluences of up to 11013 ions cm-2. Specimens irradiated with 3MeVu-1 ions were subsequently annealed for 4h at 350 degree C. Ion-irradiated samples including those heat-treated were studied using in situ temperature-dependent diffraction of high-energy X-ray synchrotron radiation (wavelength of 0.020689nm). Cyclic heating-cooling regimes were applied during the measurements. A tendency towards a higher degree of disorder was revealed as a function of the ion fluence in both types of alloys. During the first heating-cooling cycle, a remarkable hysteresis is observed in the position and line width of the first diffraction peak, especially in the as-quenched irradiated alloys. The hysteresis increases with rising ion fluence but vanishes completely after the first heating-cooling cycle. No hysteresis is found in the irradiated and subsequently annealed alloys. The irradiation-induced structural modifications have some features similar to the effects caused by mechanical deformation.