Effect of magnetic fields on the formation process of micro- and nanostructures in metals and high-entropy alloys molten

Objective: to explore the effect of magnetic fields on the formation process of nanostructures in metal melts on the example of Ti-Y and AlCoCrFeNi systems with the focus on the development mechanism of micro-and nanostructures induced by the combination of thermal capillary and magnetohydrodynamic instabilities on the “plasma/melt” interface. A principal method adapted in this study is a linear analysis of thermocapillary flow instability of a melt affected by a magnetic field. It involves establishing a relationship between a growth rate of perturbations and a wavelength. Using the obtained relationship, we determine a wavelength responsible for a maximal growth rate. It is the wavelength that dictates most probable dimensions of structure elements on the surface of metal systems. The most significant outcome to emerge from the study is that a maximal growth rate in the Ti-Y system affected by magnetic fields falls on wavelengths λ = 18 µm and λ = 294 µm. A magnetic field with a strength of 5 × 103 A/m has no effect on the displacement of the first maximum, whereas the second maximum occurs at λ = 293 µm. Once the AlCoCrFeNi system is unexposed to a magnetic field, a maximal growth rate of perturbations falls on a wavelength of 705 µm, while it is registered at λ = 1577 µm in a magnetic field of 5 × 103 A/m. Under the consideration of the evaporation pressure a maximal growth rate migrates into the micro-and nano-range and a threshold value of a magnetic field strength increases up to 106 A/m.