Glass forming ability and magnetic properties of Fe-B-Si-EM (EM = Ti, Zr, Mo, and Hf) alloys with high iron content

A series of high iron content Fe-B-Si-EM (EM = Early transition metal) amorphous/nanocrystalline alloy ribbons were fabricated by melt spinning. The effects of EM on glass forming ability, thermal stability and magnetic properties of Fe84B8Si5EM3 alloys were investigated. Based on XRD patterns of the melt-spun ribbons, a completely amorphous structure forms in Fe84B8Si5Mo3 alloy, and partial alpha-Fe phase precipitates in the (200) crystal plane in Fe84B8Si5Ti3, Fe84B8Si5Zr3 and Fe84B8Si5Hf3 alloys. These alloys show excellent thermal stability, especially for Fe84B8Si5Mo3 and Fe84B8Si5Hf3 alloys; the temperature interval between the first and the second onset crystallization temperature (a dagger T-x = T-x2-T-x1) can reach 298 A degrees C. Compared with the other alloys, the Fe84B8Si5Mo3 alloy exhibits higher saturation magnetization M-s of approximately 152.8 emu/g and lower coercivity H-c of about 11.3 A/m, thereby showing excellent magnetic properties in the as-quenched state. When annealed at the temperature close to the first crystalline peak temperature (T-p1) for 0.5 h, a clear diffraction pattern consisting of three peaks appears; this pattern is identified as bcc alpha-Fe phase. Proper annealing treatment can optimize the magnetic properties. The optimal annealing temperature range is found to be 550-650 A degrees C.