Solute distribution around an entrapping pore under impact flow during upward solidification

Abstract Solute segregation around an isolated pore in a solid, resulting from bubble entrapment under impact flow during upward-advancing solidification, is numerically predicted. In addition to influencing the microstructure of structural materials, porosity in functional materials has applications in biology, tissue engineering, food preservation and addressing global warming through its impact on sea ice. This study extends a previous model by incorporating impact flow at the top surface and examines solute fields around a fully entrapped pore in the solid. The impact velocity during solidification can be regarded as the relative velocity between the liquid and the solidification front. By solving the transport equations for mass, momentum, energy and concentration using COMSOL software, it is shown that solute distribution in the solid surrounding the pore and its shape can be controlled by adjusting transport-related parameters, including transport-related factors, such as impact velocity, gravity acceleration, ambient pressure, and solid thermal conductivity, as well as metallurgical factors like Henry's law constant, mole fraction of the solute gas at the top free surface, and partition coefficient. These parameters enable preemptive management of solute segregation and the shape of an entrapped pore in solid. The predicted contact angle during solidification closely aligns with Abel's equation, experimentally confirming previously.