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Al-Ni hypereutectic alloys with various compositions were solidified under various magnetic field conditions to investigate the alignment of primary Al3Ni phases. The results showed that the application of high magnetic fields could improve the homogeneity of the primary Al3Ni phase distribution and induce the alignment of primary Al3Ni phases in the direction perpendicular to the magnetic field direction to form chain-like structures. However, the alignment was different from the orientation of the Al3Ni phases. Furthermore, the degree of the alignment decreased with the increasing concentration of Ni element. This can be attributed to the combination effects of high magnetic field and alloy composition on the concentration field around the crystallized primary Al3Ni crystals. [ABSTRACT FROM AUTHOR]

Mn-90.4wt% Sb alloy specimens were solidified under both uniform magnetic field and magnetic field gradient conditions. The solidification behavior was examined to elucidate the effects of high magnetic fields on the solidified structure evolution of this hypoeutectic alloy. The macrostructures on the longitudinal section of the alloys were investigated by optical microscopy and x-ray diffraction (XRD). The volume fraction of primary MnSb phases and the interrod spacing of the eutectic were measured by metallographic analysis. It was found that the segregation of the primary MnSb particles at the certain regions of the specimens occurred under the influence of high magnetic field gradients. The MnSb phases obtained under magnetic fields were oriented with their (h0 l) planes along the direction of the magnetic field. Both the volume fraction of primary MnSb phases and the interrod spacing of the eutectic were decreased upon the application of the high magnetic fields. [ABSTRACT FROM AUTHOR]

Abstract: We report on the influence of magnetic field strength on the alloy Tb0.27Dy0.73Fe1.95 during slow-cooling solidification. We examined the effect of magnetic field strength on microstructure, magnetization, and magnetostrictive properties of this giant magnetostrictive alloy. We found that after field-treated solidification, the microstructure of specimens had a distinct grain arrangement and displayed magnetic anisotropy. The crystal orientation changed from random in the field-free treatment to aligned along the 〈110〉 direction in flux densities of 1 and 2.2T, and along the easy magnetization axis 〈111〉 at a flux density of 4.4T. In consequence, the magnetostrictive coefficient of the samples under various stresses improved with increasing magnetic flux density. Both the d 33 and k 33 values and the energy transformation efficiency of the field-treated specimens showed strong enhancements. [Copyright &y& Elsevier]

Abstract: The effect of high magnetic fields on the nucleation behavior of Ni-90at%Cu alloys and pure Sb were investigated. It was found that the undercooling of both Ni-90at%Cu alloys and pure Sb before nucleation was increased by the application of a high magnetic field of 11.5T. An obvious grain refinement was observed in the Ni-90at%Cu alloys solidified in the high magnetic field. Such grain refinement could be linked to the increase of the undercooling. The increase in the undercooling in the high magnetic field was attributed to the suppressing effect of the Lorentz force on the convection in the melt. Such suppressing effect could delay the formation of oxides which were responsible for the heterogeneous nucleation of the materials. [Copyright &y& Elsevier]

Abstract: With the imposition of a high magnetic field up to 11.5T, the morphologic transition of the MnBi phase and the magnetic properties of the Bi–4.36wt.% and 8.25wt.% Mn alloy specimens solidified from a semi-solid state were investigated. Compared with the irregular shape and unequal dimensions of MnBi grains under 0T, the coarsened MnBi grains were connected together and tended to be parallel to the direction of the external field of 11.5T. The changes might be attributed to the Ostwald ripening of ferromagnetic grains in the isothermal holding stage and subsequent aggregation along the direction of external field driven by mutual magnetic force among the grains. The uniform orientation of the ferromagnetic MnBi grains obtained in the microstructures effectively improves the saturation magnetization of the Bi/MnBi composite materials, but the oversized grains and the defects in grains make the coercivity decrease. [ABSTRACT FROM AUTHOR]

Abstract: The magnetic properties of Fe–49%Sn monotectic alloys were investigated after the alloys were solidified with and without a high magnetic field of 10T. The results showed that there was a significant difference between their hysteresis loops measured parallel and perpendicular to the applied high magnetic fields for the solidification process. Therefore, high magnetic fields applied in solidification process increased the magnetic anisotropy in the alloys. Along the parallel directions of the high magnetic field applied in their solidification process, the saturation magnetization M s, magnetic susceptibility dM/dH M and remanent magnetization of Fe–49%Sn monotectic alloys were increased obviously, which resulted from the improvement in the aligned microstructure of Fe–Sn alloys by applying the high magnetic field to the solidification process. A modified Stoner–Wohlfarth model was introduced to explain the experimental results. [Copyright &y& Elsevier]

Abstract: The effects of high magnetic fields on the migration and rotation of TiAl3 particles in an Al–7wt.% Si alloy were studied. Without magnetic fields, the rod-like TiAl3 particles segregate at the lower part of the solidified structure. Under high uniform magnetic fields, these particles rotate to an orientation with their longitudinal axes parallel to the direction of the magnetic flux. The segregation of the particles reduces with the increase of the magnetic flux density. A negative gradient field enhances the effect of the uniform magnetic field. By altering high magnetic fields, Al–Si alloy samples containing homogeneously distributed and preferably aligned TiAl3 particles were prepared. [Copyright &y& Elsevier]

Abstract: Solidification experiments of aluminum–nickel binary alloys under uniform high magnetic fields have been conducted. The effects of high magnetic fields on the crystal orientation of Al3Ni were investigated by XRD and the alignment of primary phases Al3Ni were also analyzed. Experimental results showed that the easy magnetization axis of Al3Ni crystal oriented parallel to the imposed magnetic fields and the primary phase Al3Ni aligned perpendicular to the magnetic fields. Magnetic orientation of crystal was determined by magnetic anisotropy energy. Whereas the phase alignment should be contributed to the combined effects of magnetic orientation, crystal growth and the effects of magnetic fields on mass transport during solidification. [Copyright &y& Elsevier]

Abstract: The effects of an 11.5T magnetic field on phase equilibria of Mn–Sb system during solidification process were investigated with the aid of direct thermocouple measurements and quantitative metallography analysis. It was found that the magnetic field could increase the eutectic line and the area fraction of the MnSb in eutectics, and thus shift the eutectic point to the high Mn concentration side. It could also increase the Sb liquidus temperatures by a decreasing trend with an increasing Sb composition, but show little effect on the MnSb liquidus temperature. The above results could be related to the variation in the magnetic susceptibility during the phase transformation. [Copyright &y& Elsevier]