Magnetic permeability after-effect and the transition from Co-rich to Fe-rich amorphous alloys

Measurements of the after-effect of the initial magnetic permeability Δμ/μ , the saturation magnetostriction λ
s
and the magnetization I
s
have been performed at room temperature on Fe-rich, Co-rich and Co
75-x
Fe
x
Si
15
B
10
(x = 0-50) amorphous alloys to study the dependence of Δμ/μ on the transition metal (Co-Fe). Results for Fe-rich and Co-rich alloys lie on two distinct curves. There is a transition region between these curves, corresponding to the alloys Co
75-x
Fe
x
Si
15
B
10
(8.5 < x < 35), whose nature is discussed in terms of recent theories of the magnetic after-effect.