Glass forming ability of Nd60TM30Al10 (TM=Fe, Co, Ni, Cu, Mn) alloys

Glass forming ability (GFA) of Nd60TM30Al10 (TM=Fe, Co, Ni, Cu or Mn) alloys was studied. From X-ray diffraction measurement, highly textured Nd nanocrystallites are observed on the free surfaces of the Fe-, Mn- melt-spun ribbons, while the Co-, Ni-, Cu- melt-spun ribbons are fully amorphous. A significant difference in the phase transformation upon heating is observed between the Fe-, Mn- and the Co-, Ni-, Cu- containing alloys. No glass transition before crystallization is observed in the Fe- and Mn-alloys, but the Co-, Ni- and Cu-alloys exhibit a clear glass transition. The absence of supercooled liquid region for the Fe-, Mn-alloys is explained by the continuous growth of Nd nanocrystallites. The difference in the GFA is strongly related to the heat of mixing between Nd and TM, which is +1, −22, −31, −23, +2 kJ mol−1 for TM=Fe, Co, Ni, Cu or Mn, respectively. The origin of abnormal GFA of Nd60Fe30Al10 is discussed in terms of the formation of the metastable A1 phase.