Formation of metastable phases from amorphous state

Since Duwez et ai. prepared the first metallic glasses by rapid quenching, a large number of contributions have been published dealing with the estimation of glass-forming ability in terms of the critical cooling rate. Recently, metallic glasses have been prepared successfully also by using quenching rates of the order of 1 K s−1. It is obvious that the principal parameter determining glass-forming ability are structural and energetic relations in the material. t theories of easy glass formation focus on the role of clusters (associations) in the molten alloy. Accepting the existence of clusters in the melt, it seems evident that their role for the formation of the amorphous structure lies in the preservation of the short-range ordering of these clusters upon quenching; such ordering then inevitably has to have important influence on the formation of the nuclei of the crystalline phase forming in the amorphous structure. ort on the study of crystallization of amorphous Fe-B, Pd-Si, Pd42.5Ni42.5P15 and Pd40Ni40P20 alloys. The formation of crystalline phases has been investigated by differential thermal analysis (DTA), differential scanning calorimetry (DSC), electrical resistivity, transmission electron microscopy (TEM) and ED methods. The structures have been analyzed with respect to the concept of formation of short-range ordered clusters in the melt and of metastable phases upon crystallization.