Nanocrystallization of Fe-Based Amorphous Alloys Fe73.5Cu1Nb3Si13.5B9 by Yb-Doped Fiber Laser Overlapping Irradiation

Abstract

The paper presents a laser irradiation method for rapidly fabricating Fe-based nanocrystalline alloys using Yb-doped fiber laser with a wavelength of 1070nm by overlapping irradiation of the heated areas. The samples are annular cores rolled with 20μm-thick and 3.2mm-wide belts of amorphous alloy Fe73.5Cu1Nb3Si13.5B9, which have internal diameter of 14 mm and external diameter of 20 mm. Every side of the samples is irradiated for 15 min by fiber laser. X-ray diffraction and transmission electron microscopy (TEM) are used for microstructure analysis and observation. The samples irradiated by a defocus beam with a diameter of 7.1mm through a lens have better soft magnetic properties than directly by an original collimating beam with a diameter of 6.7mm. The dimension of homogeneous ultrafine grains is about 10nm with a bcc α-Fe (Si), which is the foundation of the excellent soft magnetic property. Uniform laser irradiation and the appropriate laser power are necessary for optimum microstructure and soft magnetic properties.