Magnetic and Thermal Studies of Iron-Based Amorphous Alloys Produced by a Combination of Melt-Spinning and Ball Milling

Abstract

In this study, we demonstrate the synthesis of an Fe78Si9B10P3 amorphous alloy by three pathways: mechanical alloying, melt-spinning and a combination of melt-spinning and ball milling. Microstructure, thermal stability and soft magnetic properties of the melt-spun and mechanically alloyed powders are comparatively studied. Ball milling of previously melt-spun samples led to an amorphous powder with an average particle size of ~2.4 μm after 20 hrs of milling. Mechanical alloying of elemental Fe-Si-B-P powders in a planetary ball mill for up to 100 hrs led only to a partial amorphisation of powder with a median particle size of ~1.3 μm. Differential thermal analysis of the amorphous ribbon revealed that the amorphous phase was stable up to ~520 °C, at which the crystallization process occurred. The melt spun ribbons exhibited excellent soft ferromagnetic behavior, including high saturation magnetization (Ms) of ~171 emu/g and a low coercivity (Hc) of ~2.8 Oe. In the 20 hrs milled ribbons, due to a probable partial anisotropy which induced by ball milling stress, the Ms value decreased slightly to ~161 emu/g but the Hc increased to ~38 Oe. The mechanically alloyed samples present a relatively lower Ms of ~154 emu/g and higher Hc of ~43 Oe. It is to be noted that the milling of ribbons is usually inevitable due to their technological restrictions in use.