Modelofconvectiveheattransferinhigh-Entropyalloys During Electron Beam Processing

A model of convective mixing is proposed for processing high-entropy melts of AlCoCrFeNi and CuBiSnInPb systems with low-energy high-current electron beams, taking into account evaporation from the surface of materials. The model is based on the idea that processing with concentrated energy flows leads to the appearance of vortex patterns in the molten layer. The mechanism of their formation lies in the fact that the presence of a temperature gradient in the melted layer leads to the occurrence of thermocapillary convection. The convective flowmodel is based on the Navier-Stokes equations, heat transfer in liquid media and boundary conditions taking into account the outflow of evaporated material. The solution of these equations by the finite element method was carried out for two cases. In thefirst case, the dependence of thermophysical parameters on temperature was not taken into account, and in the second, this dependence was taken into account. It showed that in the first case in the AlCoCrFeNi melt at the heating stage, the melt flow is laminar. The instability of this flow is observed at the "melt/solid" boundary. The cooling stage is characterized by the formation of vortex flows. The formation of vortices occurs both at a distance close to the radius of the irradiation spot and in the central region. In the case of the CuBiSnInPb alloy, the same pattern is observed, with the only difference that the convective flow processes proceed faster due to lower values of surface tension and liquidus temperature compared to the previous case. In the second case, electron beam processing leads to the formation of a multi-vortex pattern, which, developing at the heating stage, captures all new areas of the material. At the cooling stage, the fusion of vortices and the formation of a stationary laminarflow is observed.