Pinning Effect of Curie Temperature in the Sub-T _g Relaxation of FeSiBPC Glasses

By combining Differential Scanning Calorimetry and in-situ high-energy synchrotron X-ray diffraction, the sub- T g relaxation of multicomponent FeSiBPC metallic glasses (MGs) has been systematically investigated. A two-stage relaxation behaviour in a series of Fe-based MGs has been observed, indicating the pinning effect of Curie temperature. The origin of this behavior resides in the local structure departure from short-range order to medium-range order upon annealing. Analysis of diffraction and thermophysical data shows that the structural ordering involved in the β relaxation is confined and, meanwhile, facilitated by the magnetic ordering. It is mainly the medium-range rearrangements of atoms that yield the influence on magnetic ordering. This work provides new insights into the interaction between structural arrangement during relaxation and intrinsic magnetic ordering and helps to understand the inner magnet-influenced β relaxation in MGs.