Structural evolution and the kinetics of Cu clustering in the amorphous phase of Fe-Cu-Nb-Si-B alloy

Abstract

An attempt has been made to investigate the evolution of the structure of the amorphous phase of Fe-73.9 Cu-0.9 Nb-3.1 Si-13.2 B-8.9 (finemet) alloy by a combination of wide-angle x-ray scattering, small angle x-ray scattering (SAXS), Mossbauer spectroscopy and X-ray absorption near edge spectroscopy on the supposition that they would provide complementary information. Before the onset of nanocrystallization, the amorphous phase undergoes a structural relaxation resulting in small increase in the hyperfine field and a decrease in the width of the first diffraction maxima. There is an increase in the topological ordering in the system, though chemical inhomogeneity sets-in due to the clustering of Cu atoms in the pure amorphous state of this alloy. Annealing at 400 degrees C (well below the crystallization temperature) for different time durations results in occurrence of Cu clusters having fcc structure. Kinetics of Cu clustering is studied using SAXS. The incubation time for the clustering at 400 degrees C is similar to 120 min. With further annealing, the average cluster size gradually increases from the initial value of similar to 0.4 nm, reaching a value of similar to 0.6 nm after annealing for 720 min. Cluster size exhibits a t(1/2) dependence, suggesting a diffusion controlled growt

Heterogeneous dynamics of metallic glasses

“…3(a) shows the SAXS patterns of the as-cast Vit106a and Vit1 at room temperature, where the rise of the intensity IðqÞ at small scattering vector q is connected to the structure heterogeneity on medium length scale [24]. Similar patterns have also been observed in other metallic glasses [25,26]. Like in Fig.…”

The influence of an isothermal annealing process on the structure and magnetic properties of the bulk amorphous alloy FeCoBYMo

“…It is assumed that the first low-field peak is associated with the nearest neighbourhoods of Fe and the local presence of Y. 21 The second peak corresponds to the areas with less Fe, in which the 57 Fe are partly From an analysis of Figure 3, it can be concluded that post-production thermal treatment led to segregation and the emergence of areas more or less rich in iron. The data obtained from an analysis of the Mössbauer spectra are summarized in Table 1.…”

Influence of the Quenching Rate on the Structure and Magnetic Properties of the Fe-Based Amorphous Alloy

“…The low-field components have maximal values at the induction of the hyperfine field range from 6 -8 T. The separated low-field components are related to the presence of the yttrium atoms in the nearest neighbourhood of the iron atoms. Yttrium atoms are located in the first co-ordination zone and are responsible for lowering the value of the hyperfine field [18,23]. SEM images, showing the surfaces of the breakthroughs in the ribbon-and plate-shaped samples of the investigated Fe 61 Co 10 Y 8 W 1 B 20 alloy, are presented in Fig.…”

“…Images from the high resolution transmission electron microscopy (HRTEM) and electron diffraction patterns for the investigated area reveal the structure of the alloy [17]. The other considered methods of investigating the structure of the amorphous alloys are X-ray diffractometry (XRD) and Mössbauer spectrometry [18]. Connecting these four methods facilitates the accurate description of the structure of the amorphous alloys.…”