Performance improvement of industrial pure aluminum treated by stirring molten fluxes

Abstract

Removal of inclusions from molten aluminum (A001) and aluminum grain refinement were studied by thermodynamic theory and a surface renewal kinetic model. After molten aluminum poured into the rotated molten flux in batches, the inclusions were transferred into the stirred molten flux, at the same time the trace impurities in molten flux diffused into the molten aluminum droplets. Thermodynamic theory shows that wettability of the inclusions in molten aluminum is worse than that in the molten active flux. Migration of the inclusions and diffusion of the trace impurities were described with the surface renewal kinetic model. Tensile tests show that the tensile strength of treated tensile sample (as-cast) was increased by 8.59%. The fracture cracks and the dimples were homogeneous and small as shown in SEM (scanning electron microscopy) photographs. Moreover, the quantities and sizes of the inclusions in the treated tensile samples were obviously fewer and smaller than that of in the untreated tensile samples as shown in metallographs and statistical results of an image analysis software. Meanwhile, the grain sizes of treated tensile samples were smaller than that of untreated tensile samples.