Exploration of deep purification of aluminum alloy in vacuum based on adsorption of oxides by hydrogen bubbles

Abstract

This study proposes a purification method for aluminum alloys based on vacuum and stirring. The data shows that when the vacuum degree ranges from -10 Pa to -1000 Pa and the stirring speed of the melt varies between 30 rpm and 50 rpm, the hydrogen content in the alloy fluctuates slightly around 0.099 cm3/100g, while the oxygen content fluctuates around 24 ppm. Compared to the alloy under other processing conditions, the hydrogen and oxygen content in the alloy at this time are the lowest. Furthermore, compared to the untreated alloy, the purified alloy showed significant improvements in mechanical properties. The tensile strength and elongation of the alloy reach 200.1 ± 4.3 MPa and 0.71 % ± 0.02 %, respectively. The changes in mechanical properties are related to the decrease in hydrogen content and oxide reduction in the melt. Stirring generates bubbles in the melt, which adsorb oxides from the melt. Subsequently, vacuum causes these bubbles to expand. These expanded bubbles can rapidly absorb hydrogen in the melt. When bubbles with oxides rise to the melt surface, the melt is purified to a certain extent. Additionally, the attachment of oxides to the bubbles is observed through transmission electron microscopy.