Study On The Heat Treatment Process Of Fe-based Amorphous And Nanocrystalline Strip

Fe-based amorphous and nanocrystalline alloy is widely used owing to its excellent soft magnetic properties. If the alloy composition is identified in the production, the heat treatment process will be the key factors which influence the properties of soft magnetic alloy. Therefore, it's of great significance to find the optimal heat treatment process to improve the product qualified rate of the enterprise as well as the efficiency of enterprises.The study of this paper is mainly focused on the amorphous Fe73.5Cu1Nb3Si13.5B9alloy strips, the strips with the width of10mm,8mm,7.5mm and5mm are taken as samples, then they are coiled to the magnetic cores whose standards are φ18.2×φ28×10(mm),φ14×φ19×8(mm),φ14×φ17×7.5(mm),φ14×φ20×5(mm) respectively. Combined with the actual production of the enterprise, we make a thermal annealing approach to every standard magnetic core and achieve the best thermal treatment technology. Moreover, the magnetic cores with the specification of φ18.2×φ28×10(mm) are studied by the magnetic thermal treatment, then we compared the influence of the magnetic thermal treatment on the trips properties with the three different methods.The research results of the vacuum thermal treatment indicate that the best holding temperature of the vacuum thermal treatment is547～555℃, the best holding temperature time is80～100min, the best tapping temperature is350℃for the amorphous Fe73.5Cu1Nb3Si13.5B9alloy strips. The best holding temperature decreases as the weight of the magnetic core reduces (namely volume decreases). For example, the magnetic core which is coiled by the10mm width amorphous strips weighs around21g, its best holding temperature of vacuum thermal treatment is555℃; while the magnetic core which is coiled by the7.5mm width amorphous strips weighs around3.2g, and its best holding temperature is547～549℃.When the amorphous degrees of Fe73.5Cu1Nb3Si13.5B9strips decrease, the best thermal treatment holing temperature should be reduced appropriately.The research results of the magnetic thermal treatment show that the high-frequency performance of nano-crystalline magnetic core as well as the multiple magnetic are promoted as the angle θ of complex magnetic fields decreases. The shape of hysteresis loops could be modulated by the uniaxial anisotropy (Ku) which is induced by the magnetic field annealing. Squared hysteresis loops are achieved after annealing in longitudinal magnetic field (θ=90°), the shape of hysteresis loop of cores after magnetic field (θ=45°)is similar to that after the vacuum heat treatment. Sheared loops are achieved after annealing in transverse magnetic field (θ=0°).In the thermal process of transverse magnetic field (θ=0°), with the increase of the extra magnetic field, the low-frequency performance decreases, while the high-frequency performance is improved, when the current of extra magnetic is over300A, the high-frequency performance of magnetic core changes little. The optimum transverse magnetic field (θ=0°) annealing is as follows:the annealing temperature is maintained at520℃, the holding time is90min, the magnetic field current is300A, the finish annealing temperature is200℃.