The influence of composition and aging on the Curie temperature of metallic glasses

The influence of composition, particularly glass formers P,B,C, and Si and transition metals Ni and Co, on the Curie temperature T
c
and the change in T
c
upon isochronal annealing of Fe based glasses is reported. Magnetic order-disorder transition in a "liquid" state is manifested for some (Fe,Co) glasses. The T
c
vs. y curves of some Fe
100-y
G
y
glasses are seen to exhibit a maximum. Here G represents glass formers. T
c
increases by 2 ∼ 4 K with annealing just above T
c
for all glasses observed. With further increase in annealing temperature, T
c
continues to increase for B and Si containing glasses, while for glasses containing P and C, T
c
tends to decrease. The influence of metalloid addition and alloying among Fe, Co and Ni on T
c
of metallic glasses will be interpreted in the framework of the Bethe curve.