Mg-Gd-Y-Zr合金在773和823K热处理时的氧化行为

Oxidization of Mg-Gd-Y-Zr alloy during heat treatment process at 773 and 823 K

采用金相显微镜（OM）观察、X线衍射（XRD）、扫描电镜（SEM）和能谱分析（EDS）等分析测试技术，研究Mg—Gd-Y-Zr合金在773和823K热处理时的氧化行为。研究结果表明：合金热处理后表面氧化物的主要成分为Y2O3和Zr2Gd2O7的混合物；合金在773K保温48h热处理后，表面被轻微氧化，显微组织与热处理前无明显差别；合金在823K保温48h热处理后表面氧化严重，形成较厚氧化层，氧化层中沿晶界分布有很多尺寸为5～10μm的方形及形状不规则粒子；合金在773K热处理时不需用保护气氛，而在823K热处理需用保护气氛。

The oxidation behavior of as-cast Mg-Gd-Y-Zr alloy during heat treatment process at 773 and 823 K was studied by using optical microscopy, X-ray diffraction, and scanning electron microscopy. The results show that the thin layer formed on the surface of Mg-Gd-Y-Zr alloy during heat treatment process is mainly composed of Y2O3 and Zr2Gd2O7. Being heat treated at 773 K for 48 h, the surface of Mg-Gd-Y-Zr alloy is oxidized so slightly that there are no many differences between surface layer and secondary surface layer while there is an oxidizing layer formed which contains a lot of RE-rich particles when being heat treated at 823 K for 48 h. Mg-Gd-Y-Zr alloy should be protected by other gases during heat treatment process at 823 K and need not be protected at 773 K.