Oxidation resistance of Mg-Y alloys at elevated temperatures and the protection performance of the oxide films

JOURNAL OF ALLOYS AND COMPOUNDS

卷:749

Article

Yu, Xiaowen¹  Jiang, Bin^1,2  He, Junjie¹  Liu, Bo³  Pan, Fusheng^1,2 

[1] Chongqing Univ, Coll Mat Sci & Engn, State Key Lab Mech Transmiss, Chongqing 400044, Peoples R China

[2] Chongqing Acad Sci & Technol, Chongqing 401123, Peoples R China

[3] Chongqing Changan Automobile Co Ltd, Chongqing 400023, Peoples R China

关键词: Mg-Y alloys;    Thermogravimetric analysis;    Oxidation;    XPS;    Corrosion;   

DOI  :  10.1016/j.jallcom.2018.03.342

来源: Elsevier

【 摘 要 】

Oxidation behaviours of Mg-xY (x- 0.5, 1.0, 1.7, 3.7 and 5.5 wt%) alloys were investigated below melting temperature (550-625 degrees C) in dry air. The corrosion protection properties of the high-temperature oxide films on Mg-xY alloy matrix in 3.5 wt% NaCl solution were explored. The results showed that oxidation resistance of the Mg-Y alloys increased as a function of addition of Y. Mg-5.5Y alloy exhibited the highest oxidation resistance. The oxidation behaviours of the Mg-Y alloys depended on Y content and the oxidation temperature. Importantly, the oxide films of the Mg-Y alloys were transformed from a loose MgO-rich film to a compact Y2O3-rich counterpart that suppressed inward diffusion of oxygen and thus prevented further oxidation. Owing to the higher diffusion rate of Mg2+ ions compared to that of Y3+ ions in the oxide film, Y2O3 was primarily forming at metal/oxide interface, and MgO was formed at oxide/air interface. Hydrogen evolution tests indicated that the formation of such compact Y2O3-rich film was beneficial for improving the corrosion resistance of Mg-Y alloys in 3.5 wt% NaCl solutions. However, due to the existence of a large fraction of Mg24Y(5), the protective role of Y2O3-rich films was deteriorated in oxidized Mg-5.5Y alloy. (C) 2018 Elsevier B.V. All rights reserved.

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