Production of a magnetic material with the ability to change from very soft to semi-hard magnetic

Development and magnetic properties of an alloy that can change from very soft to semi-hard magnetic are reported. We found that as quenched ribbons of Fe_75.3Pt₈B₁₂P₄Cu_0.7 alloy are amorphous by X-ray. Heat treatment in the temperature range of 400-450°C causes formation of many α-Fe grains in the amorphous matrix. Hard magnetic L1₀ FePt grains appear at ∼520°C. This alloy shows a high saturation magnetic flux density [B_s (≈ M_s)>1.55T] along with the ability to vary coercivity (H_c) from ∼25A/m to 11000A/m. The H_c can be increased further to more than 21000A/m, but at the expense of a significant decrease in B_s. The ability to control magnetic properties lies in a precise control over the soft and hard magnetic phases, which are strongly exchange coupled.