Effect of Annealing Temperature on the Soft Magnetic Properties of Fe70.43Nb10.77Si15.77Cu2.34B0.69 Amorphous Aanostrips at 20K, 300K

Since Fe-based amorphous alloys are widely used in magnetic separators, sensors and other fields, it is of practical significance to carry out research on amorphous strips used in this field.The effects of annealing temperature on the soft magnetic properties of Fe70.43Nb10.77Si15.77Cu2.34B0.69 amorphous nanostrips with 25 μm and 28 μm thickness prepared by the single roll cold method were investigated at 20 and 300K.Five specimens were annealed at472.12K, 672.12K, 772.12K, 822.12Kand 872.12K, respectively, and their microstructure and magnetic properties were tested viametallographic microscopy, X-ray diffraction, and vibrating specimen magnetometer. At cryogenic temperatureof 20K, specimens annealed at 672,12K exhibited the best magnetic properties, including the coercive forceof8.1265A/m, saturation magnetic induction intensity of1.4351T,and its residual value of 0.2462T. The comparative analysis of experimental results obtained strongly indicates that the soft magnetic properties of the amorphous alloy are significantly improved by the particular annealing treatment.

Magnetic Properties of Pure Iron with Respect to Different C/Si Ratios and Grain Sizes

Pure iron with C/Si > 1 and C/Si < 1 was smelted by a vacuum arc furnace, and the grain size was controlled through different heat treatments. The microstructure of pure iron was observed by using an optical microscope, and the grain size was subsequently measured and calculated. Finally, the coercive force, saturation magnetic induction, and permeability were measured using a vibrating sample magnetometer. The results indicate that the coercive force increases with decreases in the average grain diagonal size. An increase in the uniformity of the grain increases the saturation magnetic induction. The permeability depends on the average grain diagonal size and the uniformity of the grain as well as the chemical composition of pure iron.

Effect of High Energy Ball Milling on Structures and Properties of Atomization Fe-Based Nanocrystalline Soft Magnetic Powders

The microstructure and strain of gas atomization and water collection Fe73Si3B24 soft magnetic alloy powder treated by high energy ball milling were investigated via SEM and X-ray diffraction. And the magnetic properties of those powders were studied via VSM (Vibrating Sample Magnetometer). The results show that the atomization powders almost exhibited spheric or ellipsoidal shape. The averaged particle size was 104.94 μm. The main phases were composed of α-Fe (Si) and amorphous phase. As ball milling time went on, the interplanar space, amount of amorphous and crystal microstrain of the powders increased, while the grain size decreased. The peak for the (110) crystal plane of α-Fe (Si) phase widened, while the peaks for (200), (211) crystal planes weakened. These three peaks shifted towards to small angle direction. The saturation magnetic induction of treated powders was steady, and the coercivity of samples increased.

Magnetic and Mechanical Properties of Directionally Solidified Fe-6.5wt.%Si Alloy

Directional solidification technique was employed to produce Fe-6.5wt.%Si alloy with coarse columnar-grain structure, which was almost single crystal. The sectional diameters of columnar grains range from 2.2 to 6.8 mm. The saturation magnetic induction was 2.39 T. In this work, grain growth started from either a Fe-6.5wt.%Si crystal which was not melted at bottom of the specimen or a freely nucleated Fe-6.5wt.%Si crystal as the specimen was completely melted. It was found that the starting situation of the directional solidification plays an important role in the crystal orientation, and hence in properties.

Research of Magnetic Induction Intensity on Magnetic Abrasive Finishing

As a kind of precise surface finishing technology, magnetic abrasive finishing has wide application, low cost, high efficiency, good effects, and other advantages. Magnetic induction intensity is one main parameter affecting finishing effect and efficiency of magnetic abrasive finishing. Saturation magnetic induction intensity for different magnetic abrasives is defined through test device designed by ourselves. Affecting rules of saturation magnetic induction intensity is discussed by experiments, which provide basis for parameters selection and practical application of magnetic abrasive finishing.

Fe86.5Zr7B3Cu3.5 Nanocrystalline Ribbon Prepared by Melt – Spinning Technique without Annealing

Fe86.5Zr7B3Cu3.5 nanocrystalline ribbon can be directly fabricated by melt – spinning technique with an appropriate quenching speed without annealing processes. The average grain size of α-Fe for Fe86.5Zr7B3Cu3.5 as quenched ribbon prepared with a quenched speed V=40 m/s is about 10-13 nm estimated from X-ray diffraction and TEM observation. For Fe86.5Zr7B3Cu3.5 nanocrystalline as quenched ribbon (V=40m/s), the saturation magnetic induction Bs is 1.47 T, permeability μe at 1 kHz is 25600 and saturation magnetostriction λs is -2×10-6. The magnetoimpedance value Z/Z0 of the Fe86.5Zr7B3Cu3.5 nanocrystalline as quenched ribbon reaches –38.32 % under H=7162 A/m. Our present results reveal a novel route to fabricate the nanocrystaline ribbons with excellent soft magnetic properties and giant magnetoimpedance.