Directed crystallization of glass‐coated microwires. Issue 2 (3rd February 2016) - Larin, V.
Abstract : In this work, the directed crystallization of glass‐coated magnetic microwires of Co‐rich composition is realized with the aim to develop a novel technique for micro‐magnet fabrication. The onset of the process is caused by local overheating above the primary crystallization temperature while the rest of the wire sample is at the temperature slightly below the crystallization temperature. This creates the conditions for spontaneous formation of microcrystallites at the wire edge and the movement of the crystal–amorphous interface along the wire. It was found that the directed crystallization is possible in a narrow temperature interval of 5–7° near the crystallization temperature. The effect of the directed crystallization on the magnetic properties is evident from a giant increase in coercivity, up to 1000 times. The directed crystallization was also assisted by application of a magnetic field which resulted in greater increase in coercivity, up to 1500 times and the coercivity value reached 69400 A m −1 . For comparison, at a standard crystallization the coercivity increases by 8–10 times being in the range of 2000–4000 A m −1 . The developed micro‐magnets can find a range of applications in miniature sensors, actuators, and manipulators.