Magnetostatic interactions in a duplex ferromagnetic alloy

The chill-cast alloy, Fe
75
Si
15
B
10
, consists of submicron rods of Fe
2
B, a magnetically "hard' phase with high T
c
, in a matrix of Fe
3
Si, a "soft" phase with low T
c
. Magnetic properties change markedly on cooling through 590°C, the T
c
of Fe
3
Si, and 245°C, where the magnetocrystalline anisotropy of Fe
2
B changes from easy-axis to easy-plane. The unusual magnetic and thermomagnetic behavior observed is discussed in terms of the short-range and long-range magnetostatic interactions between the two phases.