In situ transformation of local structure and hyperfine interactions are simultaneously followed in real time during temperature annealing of metallic glasses.
TRIP-steels offer a good combination between strength and ductility. Therefore TRIP-steels are widely used in the automobile industries. The aim of this work is to study the stability of involved phases during heating and to identify the kinetics of the occuring phase transformations. For that purpose, in-situ diffraction measurements, using high energy synchrotron radiation were conducted. The analysis revealed the decomposition of the metastable austenitic phase into carbide and ferrite along the heating process and the regeneration of the austenite by further heating of the sample.
Diffraction experiments on electromagnetically levitated Nd-Fe-B alloys during solidification of the undercooled melt have been performed at the European Synchrotron Radiation Facility (ESRF). By using high intensity synchrotron radiation complete diffraction spectra could be detected within a short period of some seconds thus enabling the observation of metastable solidification products that exhibits a limited lifetime. A metastable phase that crystallizes in wide composition range and that initiates the solidification of the stable Nd2Fe14B1-phase (φ-phase) have been observed.
ABSTRACTNanometric films of iron oxides (Fe3O4, α and γ Fe2O3) of high crystalline order and purity are epitaxially grown on α-A12O3(0001) by atomic oxygen assisted MBE. A complete characterization of the films structure has been performed by in situ LEED and RHEED, and ex situ GIXRD using synchrotron radiation. The films grown at room temperature and post annealed at 400°C and 700°C (po2=10−6 Torr) are respectively metastable γ-Fe2O3 (111) and α-Fe2O3 (0001). For a substrate temperature of 450°C during growth, Fe3O4 (111) is directly obtained. GIXRD shows an in-plane expansion of the films, which decreases with thickness (0.8 and 0.2% for film thickness of 20 and 80 Å, respectively).
Evolution of structure and local magnetic fields during crystallization of HITPERM glassy alloys studied by in situ diffraction and nuclear forward scattering of synchrotron radiation