Effect of carrier gases on the entrainment defects within AZ91 alloy castings

An entrainment defect (also known as a double oxide film or bifilm) acts void containing an entrapped gas when submerged into light-alloy melt, thus reducing the quality and reproducibility of final castings. Previous publications, carried out with Al-alloy castings, reported that this trapped could be subsequently consumed by reaction surrounding volume negative effect defects. Compared Al-alloys, within Mg-alloy might more efficiently due to relatively high reactivity magnesium. However, research defects Mg alloys has been significantly limited. In present work, AZ91 alloy castings were produced under different carrier atmospheres (i.e., SF6/CO2, SF6/air). The evolution processes contained in suggested according microstructure inspections thermodynamic calculations. formed have similar sandwich-like structure, but their films combinations compounds. use gases, which associated entrained-gas consumption rates, affected