•High magnetic field affects both thermodynamic and kinetic of thermally activated transformations.•It is possible to obtain unique structure in differnt materials with via high magnetic field ...treatment.•Application of high magnetic field is effective non-contact way of enchantment functional properties.
The paper presents new investigations of high magnetic field (HMF) effects on phase and structural transformations as well as historical development of the problem. The regularities of structure evolution under simultaneous action of heat treatment and high magnetic field have been studied on different alloys. It was shown, that magnetic field can affect thermodynamics and kinetics of transformation, which results in changes in the phase composition, crystallographic texture, rate of transformation, morphology of precipitating particles, and other effects. The observed phenomena strongly depend on magnetic properties of phases involved into transformation such as magnetic moment, magnetic susceptibility, magneto-crystalline anisotropy, magnetostriction. The review comprises the main results of modern researches into the influence of magnetic field of tens Tesla on the phase and structural transformations in materials with different type of magnetic ordering. Further research directions of HMF effect on the thermally activated transformations are proposed.
The structure and crystallographic texture formation processes in two Fe–Ga magnetostrictive alloys during annealing of deformed samples under high magnetic field (HMF) 20 T have been studied. It was ...shown that the effect of the magnetic field on the structure transformation during annealing depends on the features of the recrystallization in alloys. In the case of recrystallization in a single-phase binary Fe-Ga alloy, the application of HMF along the rolling direction promotes the formation of grains along this direction. This leads to a twofold increase in the magnetostriction of the polycrystalline sample. In the same alloy, but with the presence of particles of the second phase, HMF does not affect the texture. The reasons for this phenomenon were discussed. In addition, it was found that in both alloys, the application of HMF during annealing retards the processes of structure evolution.
•High magnetic field (HMF) 20 T retards recovery and recrystallization processes in deformed Fe–Ga alloys.•In binary Fe–Ga alloy annealing under HMF led to significant texture changes and, consequently twofold increase in magnetostriction.•This effect is absent in the FeGaB alloy, where particles of the second phase change the regularities of recrystallization.
•High magnetic field (HMF) promotes D03–L12 transition in Fe-Ga alloys.•Effect is stronger in the overstoichiometric Fe-27%Ga.•After HMF annealing saturation magnetization significantly increases.
...The effect of a high magnetic field (25 T) on the D03 to L12 phase transformation in two Fe-Ga alloys with 24 and 27 at.% Ga during isothermal annealing at 475 °C is investigated using neutron diffraction and magnetization measurements techniques. It is proved that annealing in the magnetic field increases the amount of fcc – derived L12 phase in both samples. This effect is stronger in the Fe-27%Ga alloy as compared with the Fe-24%Ga alloy. The reasons for enhancing the D03 to L12 phase transition in the magnetic field are discussed. We suggest that the most significant increase in the transformation rate is related to a decrease in the energy barrier between the phases involved in the transformation process.
The texture of deformation and primary recrystallization in copper-nickel alloys with the addition of a small amount of refractory elements such as Nb, Mo, Ta and W was studied. Based on the X-ray ...analysis of the deformation texture using the orientation distribution function, it was shown that the volume fraction of the C and S components in alloys is greater than the double volume fraction of the unfavorable component B. In accordance with this criterion, after primary recrystallization in all the studied alloys, a sharp cubic texture {100}< 001 > was obtained with a volume fraction in the± 10° region of more than 95%. Alloying with refractory elements significantly increases the strength of the base copper-nickel alloy by the mechanism of solid-solution hardening. The evaluation of the mechanical characteristics showed that the increase in the yield stress in the studied alloys is from 25% to 45% with relative to Cu-40% Ni alloy.
•Doping of the Cu-Ni HTSC substrate with a small amount of refractory elements.•Tape substrates were obtained by cold rolling and recrystallization annealing.•Textural analysis of the tapes was carried out using the ODF and EBSD methods.•The ratio of components in rolling texture is a criterion for obtaining sharp cube texture.•Mechanical characteristics of tape substrates made of ternary alloys are analyzed.
The deformation behavior of (Fe83.4Ga16.6)99.9NbC0.1 non-textured polycrystalline alloy during hydrostatic extrusion was investigated. Cold deformation 53% of the as-cast sample without prior high ...temperature deformations was achieved. In the process of deformation, a sharp axial texture develops. The deformation mechanisms are both slip induced crystal rotation and twinning. The development and growth of other orientations including the desired occur during primary recrystallization. The EBSD method was used to study the features of these phenomena. The volume fraction of preferential orientations after various modes primary recrystallization was estimated. volume fraction amounted 14.4 and 18.6% after annealing 800 and 950 °C respectively. A correlation between the texture of recrystallization and magnetostriction was established.
•Hydrostatic extrusion makes it possible to cold deform Fe–Ga alloy without cracking.•During cold hydrostatic extrusion deformation, both slipping and twining processes are activated.•Twinning result is η nucleus ( //deformation direction) formation which grow during primary recrystallization.
For the first time, the production of FeGa ingots by the centrifugal casting method was proposed and implemented. Centrifugal force acting on the melt results in lower porosity and almost half the ...grain size after solidification compared with conventional gravity casting. Stress-strain diagrams were obtained in compression mode for the analysis of mechanical properties. Improved ductility after centrifugal casting is attributed to smaller grain size and lower porosity.
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Based on the measured physical properties of the Fe–Ga alloy, it was found that a decrease in the material thickness to 0.3 mm leads to an acceptable level of eddy current losses at high-frequency ...magnetization reversal (20 kHz). Recommendations have been developed on the choice of rolling modes to achieve the required thickness. The modeling of rolling according to the proposed mode is implemented, the distributions of deformation, stresses, and temperature for each pass were obtained. The results obtained are analyzed in the context of the relation between the features of deformation and the processes of crystallographic texture formation.
The processes of recovery and recrystallization in the coldrolled alloys Fe-3%Si, Fe-50%Ni, and Ni-30%Co subjected to annealing at temperatures below and above the Curie point under a high direct ...current (DC) magnetic field of 10–29Т have been studied. It is established that application of external magnetic field in the course of heat treatment at temperatures below the recrystallization temperature and Curie point retards the processes of material softening. The formation of crystallographic texture initiated by magnetic field starts upon the recovery during the pre-recrystallization magnetic annealing. Then, in the course of subsequent annealing at the recrystallization temperatures without magnetic field, there takes place the development of preferable orientations. The magnetic field annealing favors the formation of such texture components in which the easy-magnetization axis coincides with the direction of the magnetic field applied. This is evidenced by the textures formed in the Fe-50%Ni alloy (easy axis ) and Ni-30%Co alloy (easy axis ).
The structure and texture in recrystallized sheets of nonoriented electrical steel rolled according to different modes have been studied in this work. It has been shown that a decrease in the degree ...of deformation upon the final rolling leads to an increase in the ratio of the volume fractions of orientations that are favorable and unfavorable for the formation of optimal magnetic properties.
In a flat single crystal of Fe-3%Si alloy with (1 1 0)0 0 1 orientation, regions with (0 0 1)1.-1.0 orientation (deformation twins) were created by rolling at a low temperature. After cold rolling at ...80% at an angle of 45º to the 0 0 1 direction, a (1 1 2) 1.-1.0 deformation texture was formed. In the recrystallization process during annealing of such a sample, a polycrystalline structure having a nearly cubic texture (0 0 1) 1-1.0 is formed. It is demonstrated that annealing under a high DC magnetic field enhances the cubic texture sharpness as compared to annealing carried out under similar conditions without a magnetic field.
