Thermal Expansion of NANOPERM-type Alloys from In-situ X-ray Diffraction

NANOPERM-type alloys with nominal compositions of (Fe(1-x)Co(x))(76)Mo(8)Cu(1)B(15)(x=0 and 0.5) were prepared by a single-roller melt-spinning technique. Temperature evolution of the as-quenched ribbons during constant-rate heating (10 degree C/min) was continuously followed using a high-energy (88 keV) X-ray diffraction (XRD), performed on the ID 11 undulator beamline at the ESRF (Grenoble, France). MOssbauer spectroscopy and XRD confirm an amorphous nature of the melt-spun ribbons. Furthermore, M6ssbauer spectroscopy reveals a significant change of magnetic state of the as-quenched precursors when substituting Fe by Co (x=0.5). Analyzing a series of XRD patterns in a reciprocal space yields a thermal expansion of the amorphous alloys providing an insight about the thermally activated effects such as relaxation and crystallization.