,Problems of the production, investigation, and use of a microwire with an amorphous vein structure are discussed. It is determined that the magnetic properties of microwires depend heavily on the domain structure. It is established that a domain-free structure, which is characterized by a high coercive force, is also possible in a microwire. The phenomenon of natural ferromagnetic resonance (NFMR) in an amorphous microwire in the range of superhigh frequencies is investigated experimentally. The significance of an internal field of anisotropy, which gives rise to NFMR is examined. Theoretical relationships describe experimental data on NFMR well. The procedure used to produce cast microwire in glass insulation has been developed for some time [1]. Casting is carried out from a molten sample of alloy, which is placed in a glass tube and held in the suspended state by an electromagnetic field. The demagnetized glass tube is drawn into a capillary and wound on a take-in reel. The capillary is filled with metal under certain casting conditions. To achieve a stable casting process, and also to increase the cooling rate, the resulting microwire is passed through a stream of coolant. In industry, microwires of many metals and alloys are fabricated by this method (called the Ulitovskii method). These microwires have come into the most widespread use for the fabrication of resistor components: precision resistors, resistance-type strain gauges, circuit resistance elements, voltage dividers, precision RC filters, etc. Moreover, they are used to fabricate transformer windings, inductance coils, etc. A high cooling rate is called for in the procedure used to produce microwire in glass insulation. The cooling rate of the vein is 105-107 deg/sec. These cooling rates are adequate for the formation of amorphous structures in many traditional amorphous alloys. To stabilize the casting of micrwire, however, it is necessary to introduce additives to certain alloys. An amorphous structure is obtained in cobalt-, iron-, and nickel-base alloys with metalloids (boron, carbon, and silicon). To enhance the adaptability of the casting process to manufacturing, Mn, Cr, Ce, Gd, Cu, and other elements are introduced to the alloys. The adaptability of thermally-stable amorphous alloys to manufacture depends to a large degree on their composition. We used alloys with a compositon close to the eutectic in which a glassy structure is formed comparatively easily. The following phases may form in the alloy, depending on its composition, the cooling rate, the diameter of the microwire vein, and the thickness of the glass insulation; a supersaturated solid solution, a nonequilibrium crystalline phase, and an amorphous phase. A solid solution is produced primarily for type Fe-B-C alloys. Only veins of a small diameter (1-2 #m) contain an amorphous phase. Veins of type Fe-B-Si-C alloys with a diameter of 5-10/~m had both a completely amorphous structure, and a supersaturated solid solution (which has a lower H e value). Veins of type Fe-B-Si alloys with a 15/zm diameter which are close to the eutectic composition contain amorphous components. It should be noted that the positive effect of Carbon additives on the adaptability of the alloys investigated to manufacture is established during the casting of microwires.
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Dec 1, 2019
V.S Kalashnikov + 8
Open Access
