The Study Of Thermal Stability And Soft Magnetic Properties Of Fe(Co)-Hf-B-Cu Alloys Treated By Low-frequency Magnetic Pulse

In this paper, the soft magnetic amorphous Fe52Co34Hf7Be6Cu1were prepared by using the single roller quenching method made the high purity metals as raw materials. And then the amorphous were treated on the low-frequency magnetic pulse equipment to form nanocomposite alloys. In order to optimize the magnetic properties, made use of low temperature annealing method after the magnetic pulse treatment.The followings are details:1. Chemical constituents of Fe52Co34Hf7B6Cu1alloys were designed in this article. By melting the master alloy for4-5times ensure to get homogeneous master alloys. Used the single roller quenching method by controlling the roller speed (49m/s or45m/s) and changed the preparation of raw materials (B or FeB) to control the thickness and quality of the amorphous ribbons.2. The samples were analyzed by X-ray diffraction (XRD), and the results indicated that they all had amorphous packets which confirmed the samples could be complete amorphous. The transmission electrical microscopy (TEM) analysis indicated that the diffraction rings of Fe52Co34Hf7B6Cui were dispersed cyclic structure, and the pattern of the matrix was homogeneous. It could prove that they were in amorphous state. Mossbauer spectrum (MS) analysis indicated the as-quenched alloy presented a typical broadened and overlapped sextet, and the second and fifth peaks were higher than the first and the sixth peaks obviously, which confirmed amorphous state.3. The amorphous samples were measured by Differential Thermal Analysis (DTA). There were two exothermic peaks on the DTA curve, and as the heating rate increased, the peaks moved to the high temperature direction. From the calculated activation energy results, the most stable samples could be obtained by using the high roller speed and pure Bron. The highest activation energy value reached to280.9KJ/mol.4. The low frequency magnetic pulse treatment could lead to the microcrystallization of amorphous alloys at room temperature. The volume of crystallization increased with increasing field strength, under the condition of constant the acting time and frequency. And the values of activation energy of crystallization were inversely proportional to the volumes of crystallization, directly proportional to the hyperfine magnetic fields of amorphous phase. The activation energy were generally lower after treatment, and the more stable state was obstained at the condition of magnetic field strength200Oe, frequency30Hz, the acting time240s.5. The original samples、the samples after the magnetic pulse treatment and then after annealing under different conditions were measured by Vibrating Sample Magnetometer (VSM). The results showed that the samples after low frequency magnetic pulse treatment had higher saturation magnetization and smaller coercivity. And after annealing, magnetic properties of the samples were even better than just magnetic field treated samples. Under the same holding time (30min), temperature100℃could induce the better magnetism than others under higher temperature. Under the same annealing temperature (200℃), the holding time (45min) could due to magnetic optimization. Based on an overall consideration of various factors, the condition of200℃/45min could get the smallest coercivity-61A/m, which had good soft magnetic properties.