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

作　　者：Tian Li J.M.T.Davies Xiangzhen Zhu 

机构地区：[1]University of Birmingham,Birmingham 8152TT,United Kingdom [2]Grainger and Worrall Ltd,Bridgnorth WV155HP,United Kingdom [3]Brunel Centre for Advanced Solidification Technology,Brunel University London,Kingston Ln,London,Uxbridge UB83PH,United Kingdom

出　　处：《Journal of Magnesium and Alloys》2022年第1期142-159,共18页镁合金学报（英文）

基　　金：funding from the EPSRC Li ME grant EP/H026177/1。

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

关 键 词：Magnesium alloy CASTING Oxide film Bifilm Entrainment defect Reproducibility 

分 类 号：U466[机械工程—车辆工程] TG146.22[交通运输工程—载运工具运用工程]