Change of permeability in amorphous ferromagnetic ribbons by heat treatment

The initial permeability μ
i
the loss factor
\tan\delta
and the disaccommodation of non magnetostrictive Fe
5
Co
70
Si
15
B
10
and high magnetostrictive Fe
78
Si
10
B
12
and Fe
80
P
13
C
7
amorphous ribbons were measured as a function of temperature in the high frequency region. The initial permeability of as-prepared Fe
5
Co
70
Si
15
B
10
ribbon was observed to have maxima at about -50°C and just below the Curie temperature, and a minimum at about 280°C. For as-prepared Fe
80
P
13
C
7
ribbon, the permeability was almost independent of temperature from room temperature to about 230°C. The largest disaccommodation was observed at about 70°C for Fe
5
Co
70
Si
15
B
10
, and was not observed above 180°C.