Large magnetostriction Fe-Pt-B amorphous alloys

The saturation magnetostriction has been measured at 77 K and room temperature for amorphous alloys series Fe
80
M
x
B
20-x
with M=C, Si, Ge and Fe
83-y
M
y
B
17
with M=Ga Ge, Pt. It was found that the magnetostriction λ
s
in Fe
80
Ge
x
B
20-x
increases with increasing X in contrast to the decreased λ
s
in Fe-C-B and Fe-Si-B alloys. The increase in y of the latter alloy series causes also the λ
s
to increase at room temperature. The increment in λ
S
of Fe-Pt-B alloys was large markedly. The Fe
79
Pt
4
B
17
alloy has λ
s
of 46 × 10
^-6
at room temperature and λ
s
of 63 × 10
^-6
at 77 K, being higher than values reported for Fe based alloys to date. A linear relation between λ
s
and the magnetic moment was found to hold phenomenologically for Fe-M-B alloys with M=Ga, Ge and Pt having the increased λ
s
.