| The solid transformation of materials under the extreme condition, such as extremely high magnetic field, become a focus in the field of the materials science and engineering. Much investigation reveals that the materials show the distinguishing characteristics of physico-chemical phenomena in the abnormal condition, which not only supplies the new way to design materials, but also strongly promote the development of the new material. The materials show the strong magnetism in the magnetic field during the transformation or non-transformation. The new magnetism implies that the magnetic field can apply not only to the traditional ferromagneitic materials, but also to all materials. So we can image that the magnetic processing technology and relative investigation will have a extensive affect on the development of materials.In this paper martensitic transformation coupling with the thermal field and magnetic field was studied in the paramagnetic Ni-Ti alloy. Firstly, the samples were heated to austenization and processed by the magnetic heat-treatment with different magnetic intensity. During cooling, the transformation temperature was measured according to the resistance method. The result shows that the transformation temperature increases with raising the magnetic intensity and the magnetic field can promote the martensitic transformation. Through the investigation of TEM pictures, it is found that the martensitic variants in samples grow vertically with 5T magnetic field, instead of the triangle self-accommodation without magnetic field, and show the characteristics of oriented growth. The paper calculated the potential density of Fermi face with different shear strain by the first princible, and make use of the proportional relation of susceptibility and potential density of Fermi face to obtain the relation of susceptibility and shear strain. With introduction of the magnetic effects into the Landau theory, the improved Landau can apply to the circumstance coupling with the magnetic field and thermal field. By comparison with calculation of Landau theory, the results demonstrate that calculation fits experiments well.Hot extruded AZ31 alloy sheet was processed by the magnetic annealling,and this paper investigated the effects of the magnetic field on the recrystallization texture by the measurements of the grain size and orientation distribution of grains.In the experiments,the samples were annealleda at 400℃for 2.5 hours under different magnetic density and three samples were fixed in 10T magnetic field with the angles of 0°,45°and 90°between the rolling direction(RD) and field direction(H),respectively. XRD demonstrates that the magnetic field can influence the recrystallization texture due to the spatial relation of direction of the magnetic field and c axis of the grains in the texture. When RD is parallel to H, c axis of the texture is perpendicular to H. (0001) texture is strengthened because of the maximum of the magnetic driving force. When the RD is perpendicular to H, c axis is parallel to H. (0001) texture is weakened because of the minimum of magnetic driving force. By comparison with the (0001) pole figures in different condition, the investigation reveals that the strength of texture slightly increases when the c axis is perpendicular to H. The reason for the phenomenon is that the magnetic energy exerted by the magnetic field is much smaller than the boundary energy. However, the strength of texture increases abnormally when the c axis is parallel to the direction of magnetic field.The further investigation is still needed. Optical microstructure pictures show that the magnetic field have few effects on the mean grain sizes of samples through magnetic annealing, and the grain sizes vary drastically. Because the critical grain size of the preferable grains becomes smaller due to the magnetic field. By contrast, the critical grain size of the adverse grains become bigger, and the growth of the grain is retarded and the grains shrink. Furthermore, the magnetic driving force is not big enough to promote the grain with favorable orientation to swallow the adjacent grains,but the grain increase in some extent. As a result, the variation of grain sizes increases and the mean grain size almost doesn't change...
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