On the crystallisation behaviour of amorphous alloys of rare-earths and 3d transition metals

The crystallisation behaviour of several amorphous rare-earth-rich alloys of 3d transition metals, prepared by melt spinning, was studied by means of differential scanning calorimetry, x-ray diffraction and transmission electron microscopy (TEM). The thermal stability of these alloys is found to increase in the lanthanide series going in the direction from La to Lu. An increase is also observed in the sequence Fe, Mn, Co, Ni. The type of crystallisation taking place in these alloys is largely determined by the heat of alloying. This quantity is rather small in rare-earth iron alloys. The effect of this small heat of alloying is not so much as to lead to a comparatively low number of intermetallic phases into which the amorphous alloys can crystallise but rather to give rise to nucleation difficulties. (author)