Magnetic properties of Fe-Si-Al single crystals

Magnetocrystalline anisotropy and magnetostriction were measured for the single crystals of Fe-Si-Al alloys lying near the Sendust composition (85%Fe, 9.6%Si, 5.4%Al). The constants K
1
, λ
100
, λ
111
and λ
s
are plotted in the concentration diagram of the Fe-Si-Al system. It was found that K
1
= 0 is realized in the region of 5.5%Al, 7.5 ∼ 10%Si, 84.5 ∼ 87%Fe. Correlations among these constants and initial or maximum permeability, μ
i
or μ
m
, are shown and discussed. Both μ
i
and μ
m
measured for two picture-frame single crystals, containing 9.6%Si and 5.8%Al, decreased rapidly with increasing temperature. The highest values of μ
i
and μ
m
were 30,000 at 5°C and 210,000 at -20°C for the <100> frame, and 30,000 at 5°C and 170,000 at -20°C for the <111> frame, respectively. The coercive force increased from 10 to 45 mOe for the <100> frame, and from 12 to 70 mOe for the <111> frame with increasing temperature from -20 to 120°C.