Effect of heat treatment on the microstructure and properties of Ni based soft magnetic alloy

Abstract

A Ni-based alloy was heat treated by changing the temperature and ambient atmosphere of the heat treatment. Morphology, crystal structure, and physical performance of the Ni-based alloy were characterized via SEM, XRD, TEM, and PPMS. Results show that due to the heat treatment process, the grain growth of the Ni-based alloy and the removal of impurities and defects are promoted. Both the orientation and stress caused by rolling are reduced. The permeability and saturation magnetization of the alloy are improved. The hysteresis loss and coercivity are decreased. Higher heat treatment temperature leads to increased improvement of permeability and saturation magnetization. Heat treatment in hydrogen is more conducive to the removal of impurities. At the same temperature, the magnetic performance of the heat-treated alloy in hydrogen is better than that of an alloy with heat treatment in vacuum. The Ni-based alloy shows an excellent magnetic performance on 1,373 K heat treatment in hydrogen atmosphere. In this process, the µ , B , P , and H of the obtained alloy are 427 mHm , 509 mT, 0.866 Jm , and 0.514 Am , respectively. At the same time, the resistivity of alloy decreases and its thermal conductivity increases in response to heat treatment.

Microstructure-magnetic shielding development in additively manufactured Ni-Fe-Mo soft magnet alloy in the as fabricated and post-processed conditions

“…11a show almost constant Ms value (see Table 2). This is because Ms is an intrinsic property that can be affected only by chemical composition [41], (magnetisation is the number of atomic magnetic moments in unit volume), and all samples in Fig. 11a are the same alloy and processed with the same laser parameters.…”

“…M and Tc are intrinsic magnetic properties and their improvement with HIP and HT post-process arises from the improvement in grain size and chemical composition due to Fe and Mo immigration to the main matrix. It is worth mentioning that finishing post-processing with the HT instead of the HIP treatment results in better soft ferromagnetic properties (see Table 2), this is because HIP process, sometimes, doesn't result in a complete stress relief [44], in contrast with HT process in Hydrogen atmosphere that decreases oxides and reliving stresses [45]. Table2: Saturation magnetisation and coercivity of the AF and post-processed HT and HIP samples built with E=4.68J/mm 2 at different orientations.…”

Investigation on the Growth and Properties of Six Garnet Single Crystals with Large Lattice Constants

“…Besides, the thermal expansion coefficient increases caused by factors such as thermally induced microdefects, annealing will reduce defects in the materials and thereby the thermal expansion coefficients decrease. [33] Moreover, one thing that needs to be clarified is that the magneto-optical film is not easily to crack for when the thermal expansion coefficient of the film is close to that of the substrate. For example, the thermal expansion coefficient (about 10 × 10 −6 ) [34] of Bi-doped series YIG films is approximate to that of the substrates (about 8.5 × 10 −6 ), so that the magneto-optical film does not crack easily.…”