Effect of Al on Bulk Amorphization and Magnetic Properties of FeSnPSiB Alloys

Abstract

Structure and magnetic properties of melt-spun multi-component Fe_78−xAl_xSn₂P₁₂ Si₄B₄ (x = 0, 3, 4, 5 at%) amorphous ribbons and copper-mold-cast rods were investigated. The improvement of thermal stability was recognized with the replacement of Fe by 3∼5 at% Al in these Sn-containing alloys. The super-cooled liquid region (ΔT_x), defined by (T_x − T_g) where T_x is the crystallization temperature and T_g the glass transition temperature, increases from 46.5 K as x = 3 to the maximum value 50.2 K as x = 4. With increasing Al content, magnetic properties of annealed Fe_78−xAl_xSn₂P₁₂Si₄B₄ (x = 3∼5 at%) amorphous ribbons are: saturation magnetization decreases from 1.22 to 1.18 T; coercive force decreases from 3.3 to 2.2 A/m, maximum permeability increases from 137000 to 208000, Curie temperature lowers from 591.1 K to 578.3 K; the electrical resistivity increases from 175 to 188 μΩ-cm; and core loss is about 0.14 W/kg (50 Hz, 1.1 T external magnetic field). Bulk amorphous rods with 1 mm diameter were successfully demonstrated for the composition Fe₇₄Al₄Sn₂P₁₂Si₄B₄ by a copper mold casting method. Due to the combination of good glass forming ability and superior soft magnetic properties, these alloys will find potential applications in industries.