Manufacturing, Crystallization And Soft Magnetic Properties Of Fe-based Amorphous And Nanocrystal Alloys

The prosperity of information industry is demanding a higher standard of sensing unit.Some developed magnetic sensors have appeared their deficiency.The development of material science gives magnetic sensor a promising prospect of their invention and improvement, and the discovering of soft magnetic opens a new researching field.The magnetic instruments have some excellent applications because magnetic sensor and magnetic recording instrument have some special properties such as high sensitivity,small volume,fast response and noncontact.Amorphous and nanocrystal composed materials with high permeability,high magnetic flux,low coercive,low cores-loss and narrow frequency-diffraction are the best soft magnetic materials of world.These materials have replaced Co-based and Fe-based amorphous in various fields such as commonmode choke,high frequency switch-power, high frequency converter,zero-sequence mutual-inductor,they are also used for high sensitivity magnetic head or amplifier.In this dissertation,we selected Fe-based bulk amorphous as researching target, Lots of researching work have been carried out on manufacturing process, crystallization kinetics,microstructure,soft magnetic.Researching results show:(1) The Fe-based amorphous alloy strips were manufactured by single-roller melt spinning method.The typical amorphous shape have two clear wide peak.(2) Investigated into TEM images of annealed sample,we found homogeneousα-Fe nanocrystals were precipitated in the amorphous body.The average grain size lies between 20～60 nm and 7～13 nm.The microstructure and property of annealing Fe-based amorphous were studied by XRD and DSC.(3) Studied into the GFA of amorphous from thermodynamics,we found Fe-based amorphous have strong glass forming ability,such as low critic cooling rate,reasonable reduced transition temperature,supercooled liquid region becomes wide with the increasing of Zr and Co.(4) The content of element Zr has no marked influence on crystallization activation energy,increasing Zr could increase crystallization activation,while it reduced when content reached 10.5%,the crystallization temperature can be calculated by VFT equation.The site ofα-Fe phase peak moved to right direction with the increasing of Zr,the intensity of crystallization peak reinforced because of annealing process.(5) The initial permeability increased and coercive force reduced when annealing temperature rising from 623K to 823K, while initial permeability force reduced and coercive force increased when annealing temperature past 823K.Compared with annealing temperature, we found annealing time hasn't a marked influence on saturation induction density.Annealing temperature contributs to magnetic after effect,magnetic after effect reduced when annealing temperature increased or content of Zr increased.