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

Abstract

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 1×1013 ions cm−2. Specimens irradiated with 3MeVu−1 ions were subsequently annealed for 4h at 350°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.