High magnetic fields (HMFs) can regulate the wettability of molten metals; however, their effects on diamagnetic melts and the crystallographic-orientation dependence on substrates remain unclear. We systematically investigated molten Sn wetting on α-Al2O3 with different crystallographic orientations under HMFs, used electron backscatter diffraction to quantify grain-size changes, and quantified field effects on interfacial tensions and clarified the mechanism of orientation-dependent wetting anisotropy. Upon application of HMFs, the wettability of molten Sn on α-Al2O3 substrates was enhanced to varying degrees and increased progressively with magnetic flux density. At 6 T, the equilibrium contact angle of the Sn/(101¯0) α-Al2O3 decreased significantly by 32°. Applying HMFs enhanced nucleation and refined grains, with the greatest reduction (∼306 μm) observed in the Sn/(101¯0) α-Al2O3 system. Theoretical analysis and calculations indicated that applying an HMF reduced the liquid–gas interfacial energy and altered the solid–liquid interfacial energy and that these coupled changes affected the wetting behavior. The orientation dependence of α-Al2O3 susceptibility led to field-induced differences in solid–liquid interfacial tension and hence orientation-dependent wetting. These results reveal a direct link between field-induced changes in contact angle and nucleation enhancement, further supporting the orientation-dependent nature of magnetic-field regulation of wetting behavior.
An et al. (Thu,) studied this question.