THREE-DIMENSIONAL NUMERICAL SIMULATION AND EXPERIMENTAL STUDIES OF PURE ALUMINUM AND ALUMINUM ALLOYS DURING GASAR PROCESS

The process of melting metals in a hydrogen atmosphere and then casting into a mold, to ensure directional solidification, could result in the formation of pores within the metal−hydrogen usually grows as quasi-cylindrical pore normal to the solidification front as it is driven out of the solution. In this study, experimental and numerical analyses were performed on aluminum melt to investigate the formation of pores in the molten metal during the "GASAR" (Ukrainian acronym for gas-reinforced composite metals) fabrication process. The experimental aspect of this work was carried out on pure aluminum, and aluminum-based magnesium alloys at varying pressure and superheats processing conditions. A numerical lattice Boltzmann approach was adopted in modeling the melting-solidification process, homogeneous pore nucleation, and growth in the gas-solid material. The developed model was used to identify processing conditions in which hydrogen gas bubbles are stable in the molten metal before eutectic gas transformations in metal-hydrogen systems cause the metal to solidify. The usefulness of our numerical simulations in supporting experimental procedures aimed at understanding the complex physics phenomena inherent in the formation of ordered pore structures is demonstrated. Conditions for producing such porous material and their physics are also highlighted in this paper.