Structure evolution of soft magnetic bulk glassy alloys
By adding 0.5 at.% Cu to the Fe36Co36B19.2Si4.8Nb4 (BA100) bulk metallic glass, fully amorphous rods with diameters up to 2 mm diameter were obtained. The Cu-added glass shows a very good thermal stability but, in comparison with the Cu-free base alloy, the entire crystallization behavior is drastically changed. Upon heating, the glassy (Fe36Co36B19.2Si4.8Nb4)99.5Cu0.5 (BA99.5Cu0.5) samples show two glass transitions-like events, separated by an interval of more than 100 K, in between which a bcc-(Fe,Co) solid solution is formed. The relaxation behavior prior to crystallization, as well as the crystallization behavior, were studied by time-resolved X-ray diffraction using synchrotron radiation. It was found that both glassy alloys behave similar at temperatures below the glass transition. However, irreversible structural transformations take place when approaching the glass transition and in the supercooled liquid region.
Mihai Stoica, Parthiban Ramasamy, Ivan Kaban, Sergio Scudino, Mircea Nicoara, Gavin B.M. Vaughan, Jonathan Wright, Ravi Kumar, Jürgen Ecker: “Structure evolution of soft magnetic (Fe36Co36B19.2Si4.8Nb4)100-xCux (x = 0 and 0.5) bulk glassy alloys”, Acta Materialia 95 (2015) 335-342 URL