Evaluation of formation and evolution of microporosity in anodic copper solidification processes: Simulation and experimental validation. http://dx.doi.org/10.1007/s11663-013-9815-y

Abstract

The current study analyzes the formation and evolution of microporosity during the solidificationof anodic cooper. The aim of this study is to develop a thermofluid-formulation includingmicrostructural evolution and to perform experiments to validate some measured variables withthe respective numerical predictions. To this end, a set of experiments is carried out in coppertesting primary and eutectic phase formation together with porosity evolution. To evaluate theformation of different microstructural phases and porosity, anodic copper (99.80 pct purity,approximately) is poured into different types of molds. The effect of heat extraction on thethermofluid-microstructural response is evaluated using graphite and steel molds to promotedifferent cooling rates. The microporosity depends on the microstructural formation; hence themicrostructure needs to be firstly described. The proposed microstructural model takes intoaccount nucleation and grain growth laws based on thermal undercooling together withmicrostructural evolution. The primary phase evolution model is based on both solute diffusionat the grain scale and the dendrite tip growth kinetics, while the eutectic evolution is assumedproportional to the copper initial composition and eutectic undercooling. The microporositymodel accounts for the partial pressures of gases and the solute distribution in the liquid andsolid phases. The corresponding numerical formulation is solved in the framework of the finiteelement method. Finally, the computed temperature, solid, and liquid volumetric fractions, andpressure histories together with the final values for the radius, density, and pore volumetricfraction, are all compared and validated with the experimental measurements.