Glass formation and soft magnetic properties in Dy-containing Fe–Si–B alloys by adjusting B/Si mole ratio

Abstract The Fe87−xB8Si5Dyx (x = 1, 2, 3, 4 and 5 at.%), Fe84B8+ySi5−yDy3 (y = 1, 2, 3, 4 and 5 at.%) and Fe85B12Dy3 alloy ribbons were fabricated through the melt-spun technique. Then, the effects of B/Si mole ratio on the glass-forming ability (GFA), thermal stability and soft magnetic properties were investigated. Results showed that 3 at.% Dy addition improved the GFA of FeBSiDy alloy system, but it still exists partial crystallization. On this basis, the completely glass structure was formed in Fe84B11Si2Dy3 and Fe84B12Si1Dy3 alloys by adjusting the B/Si molar ratio. All the alloys exhibit high thermal stability, and the temperature interval between the first and the second onset crystallization temperature (∆Tx) is up to 161–196 K. Meanwhile, the Fe84B12Si1Dy3 alloy exhibits higher saturation magnetization (Ms) of approximately 137.4 emu/g and lower coercivity (Hc) of about 5.1 A/m than those of Fe84B11Si2Dy3 alloy, thereby displaying better magnetic properties in the as-quenched state. When annealed near the first crystalline onset temperature (Tx1) for different time, the two metallic-glass (MG) ribbons only precipitate a single α-Fe phase. Especially annealing for 10 min, the two alloys possess the optimum soft magnetic properties, including high Ms of 160.0–164.1 emu/g and low Hc of 3.8–6.1 A/m.