Influence Of Middle-frequency Magnetic Pulsing And Low-temperature Vacum Annealing On The Soft Magnetic Properties Of HITPERM Nano-allloy

It is known that adding element Co into the Fe-based amorphous alloy can observably enhance its heat stability and elements Cu, B, Zr can optimize the nanocrystalline alloys’ soft-magnetic performances. By Magnetic Nano-crystallization at room temperature can efficiently inhibit the embrittlement, then enlarge the application scope.This paper choose the specimens (Fe1-xCox)86Hf7B6Cu1,(Fe1-xCox)86Zr7B6Cu1,(Fe1-xCox)86Hf7B7as experimental samples. Ingots of the needed samples are prepared by vacuum arc smelting furnace and then those ribbons of about1.5mm in width and20μm in thickness are melt out by single-roller urgent cold method at49m/s.Using the X-ray diffraction (XRD), Transmission electron microscope (TEM) and Mossbauer spectroscopy (MS) to analyze these ribbons, and the X-ray diffraction patterns of the ribbons are amorphous halos only, the TEM diffraction images show widen scattered rings and the results of MS are typical broadened and overlapped sextets, the second and fifth peaks were higher than the first and the sixth peaks obviously, as well. In a word, the prepared as-cast ribbons are completely amorphous. At the same time, we discuss the influences of the elements Hf, Zr, B, Cu and the radical FeB by the detailed results of the MS on the quenched amorphous alloys.Then, all the prepared as-cast ribbons are proceed in different middle-frequency magnetic pulsing (f=1500,2000Hz.50,200oe.20min). Afterward, we analyze the changes on microstructure and the MS parameters based on different chemical element by the TEM, MS, and show the amorphous alloys get crystallized after magnetic pulsing process and the volume fraction of crystalline phase,Ψ, get bigger with the increasing of the pulsing frequency f and the magnetic field H obviously; we also achieve the elements Hf, Zr, B, Cu can affect the MS parameters such as the volume fraction of crystalline phase, the hyperfine evaluation of crystalline phase and the averaged hyperfine evaluation as well as the radical FeB.Finally, we choose the (Fe1-xCox)86Hf7B6Cu1(x=0.4) nanocrystalline alloy under the known middle-frequency pulsed magnetic field (f=2000Hz; H=250oe; t=20min) as the sample to be annealed at the low-temperature in the vacuuming condition, then the magnetic properties of the primary quenched sample, after magnetic field processing sample and annealing samples are tested by the VSM (Vibrating Sample Magnetometer) and the results testify the middle-frequency magnetic pulsed and the annealing treatment can optimize the soft-magnetic properties. We also get that the alloy annealed at100℃,30min achieved the best soft-magnetic properties (the coercive force:34A/m, the saturation magnetization:149.32emu/g), in this paper.