Structural study of a phase transition in a NiP metallic glass

The structure of NiP amorphous alloys has been the subject of several controversies, especially concerning the nature of the short- and medium-range orders. It has already been reported that these metallic glasses can exhibit polymorphism, i.e., different types of local order, depending upon the production technique. In this study, amorphous ribbons of Ni81P19 produced by two different techniques, melt spinning and electrodeposition, have been investigated. The results obtained from various types of structural analysis have been correlated: differential scanning calorimetry (DSC) and neutron diffraction during heating at different rates until complete crystallization. A hilly region in the DSC curve as well as some significant changes in the diffraction pattern could be observed prior to crystallization in both the melt-spun and the electrodeposited samples. The results are interpreted and discussed in terms of a phase transition in the material.