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The effect of a high magnetic field on the microstructural evolution of a peritectic Al―18 at.% Ni alloy during directional solidification and its dependence on pulling speed were investigated. At a low pulling speed, the application of a 2 T magnetic field triggered the appearance of a primary Al3Ni2 phase. At higher pulling speeds, a high magnetic field application induced primary Al3Ni2 phase segregation that formed close to the central alloy regions. For all pulling speeds, the application of a high magnetic field induced bulk Al3Ni/Al eutectic formation on the upper and lower parts of the alloys, and promoted elongated growth of the peritectic Al3Ni phase along the magnetic field direction. Microstructural analysis indicated that microstructural evolution that was induced by high magnetic fields can be attributed to solute migration and melt flow that is regulated by magnetic, Lorentz, and thermoelectric magnetic forces and their coupling effects during peritectic solidification.

(Tb0.27 Dy0.73)1.04Fe1.95 alloys directionally solidified in a 4 T high magnetic field were heat treated in various high magnetic fields. Changes in magnetic domain structure, magnetostriction, and magnetization of the alloys were investigated. The alloys treated at 12 T showed the highest magnetostriction, followed in descending order by the alloys treated at 0, 6, 3, and 9 T. The alloys treated at 12 T showed the highest light and dark contrast in the domain image, followed in descending order by the alloys solidified at 6, 0, 3, and 9 T. The change in magnetostriction can be mainly attributed to the alteration of the light and dark contrast in the domain image induced by the high magnetic fields. It can be proved that the high magnetic field can be effectively applied to the directionally solidification and heat treatment processes of Tb–Dy–Fe alloys to improve their magnetostrictive performance.

Wetting transitions between molten metals and different solid substrates were investigated using the sessile drop method to evaluate the possibilities of regulating wettability by high magnetic fields (HMFs) during wetting. For most wetting counterparts, the molten-metal droplet outline showed an apparent change because of the influence of HMFs. Contact angles that were measured with HMFs decreased compared with contact angles that were measured without HMFs. The temperature and magnetic-flux density had an evident but more complicated effect on the wetting transition. For reactive wetting systems, the effect of HMFs on changes of element distributions at the metal/substrate interface may lead to a variety of wetting transitions. For non-reactive wetting systems, solidified metal droplets can move from the solid substrates after wetting. No detailed and comprehensive explanations on HMF wetting-transition mechanisms exist, and further work is required. This study contributes to perfect wetting mechanisms and theories and provides a scientific approach to control wettability.

We measured the contact angles of Al and Sn drops on polycrystalline Al2O3 substrates in various high magnetic fields at different temperatures. The contact angles of both Al and Sn drops on the Al2O3 substrates decreased under high magnetic fields. These decreases strongly depend on the temperature, magnetic flux density, magnetic properties of the metal drops, and the reactivity of the metal drops with Al2O3. Our results reveal that the wetting behavior of molten metal drops on ceramics can be modified by a high magnetic field.

A specially developed experimental platform to measure the wettability of molten metals on solid substrates under high magnetic fields in combination with the sessile drop method is presented in this work. The desired magnetic field was generated by a superconducting magnet containing a channel with a diameter of 300 mm, in which the main body of the experimental apparatus was installed. The developed setup was used to observe the in situ wetting behavior of a molten metal on a solid substrate and simultaneously record sample images in real time under a high magnetic field during the wetting process. Contact angles were determined by analyzing the recorded images with the help of analytical software. Experiments using a typical molten metal and a solid substrate were conducted. The results revealed that the wettability of the molten metal on the solid substrate was obviously improved under a high external magnetic field.

The effect of a symmetrically distributed magnetic-field gradient on the microstructure and magnetic properties of solidified and semi-solid isothermally annealed Mn–89.7 wt%Sb alloy was investigated experimentally. In the absence of an applied magnetic field, primary MnSb phases had a dendritic morphology after solidification. The content of primary MnSb-phase dendrites in the lower part of the sample decreased slightly with depth. After semi-solid isothermal annealing treatment, primary MnSb phase particles in the MnSb/Sb eutectic matrix were relatively evenly distributed along the vertical axis of the sample. The application of a symmetrical high magnetic-field gradient caused primary MnSb-phase dendrites and alloy particles to distribute along the middle of the sample with a symmetrical gradient. The content of primary MnSb-phase dendrites and particles first increased and then decreased along the vertical axis of the sample. The saturation magnetization of this alloy is related to its MnSb phase content. Therefore, the saturation magnetization of the Mn–89.7 wt%Sb alloy samples that were solidified and semi-solidly isothermally annealed under a symmetrical magnetic-field gradient increased and then decreased along the vertical axis of the sample. This symmetrical distribution of the saturation magnetization intensity was caused by the magnetic force driving the Mn-enriched zone or MnSb particles towards the center of the specimen.

In this work, Tb0.27Dy0.73Fe1.95 alloys were solidified in a high magnetic field of 4.4 T at various cooling rates. Changes in the magnetostriction, crystal orientation, magnetization, and magnetic domain of the solidified alloys were investigated. The application of the magnetic field can induce orientation of (Tb, Dy)Fe2 phase. However, the effect of the magnetic field is strongly dependent on the cooling rate. The alloy solidified at 5 °C/min shows the highest magnetostriction, strongest orientation, best contrast of light and dark in the domain image, and fastest magnetization, and followed in descending order by the alloys solidified at 1.5 °C/min and 60 °C/min. The change in the magnetostriction of the alloys can be attributed to the changes in crystal orientation and magnetic domain structure caused by both the magnetic field and cooling rate.