Magnetic properties of nanocrystalline mechanically alloyed Fe-M (M=Al, Si, Cu)

Fe_100-xM_x powder blends with M=Al, Si and Cu and x⩽50 are mechanically alloyed. In all three alloy systems, disordered bcc solid solutions are formed which are unstable in the immiscible Fe-Cu system. A nanocrystalline state with average grain sizes of 15-30 nm and high internal strain is established. The saturation magnetization of mechanically alloyed Fe-Al and Fe-Si is very similar to that of the corresponding as-cast alloys. For the unstable Fe-Cu alloys, it behaves like a simple magnetic solution up to a Cu content of 30 at.%. Relatively high coercivities of up to 40 A/cm occur, indicating a predominant influence of internal stresses on the soft magnetic behavior via magnetostriction. The lowest coercivity of 3 A/cm is measured for Fe₉₀Cu₁₀