(1. 太原理工大学 材料科学与工程学院，太原 030024；
2. 新材料界面科学与工程教育部重点实验室，太原 030024)
摘 要: 通过同时加入Y和Ce获得了阻燃效果优异的Mg-Y-Ce阻燃镁合金，实现了镁合金在大气条件下的无保护熔炼，Mg-Y-Ce合金由工业纯Mg(99.9%，质量分数)、Mg-25%Y(质量分数)中间合金和纯Ce(99.5%，质量分数)在电阻炉中于保护性气氛(CO2+0.5%SF6)下熔配而成。AES(PHI550 ESCA/SAM)和XRD(X’Pert Pro MPD)表面分析结果表明：当Mg-3Y-4.5Ce阻燃镁合金在高温下暴露于大气中时，其表面膜为双层膜，外层主要由Y2O3组成，而内层Y和Ce含量极低，以Mg和MgO为主。基于高温氧化热力学分析，建立了Mg-Y合金在高温下的选择性氧化模型，获得了Mg-Y合金能够发生选择性氧化的Y浓度阈值(约为7%，质量分数)。分析了Ce在Mg-Y合金选择性氧化中的第三元素效应，Ce起到了“吸气剂”的作用，可以抑制氧向合金内部扩散，从而抑制Y元素的内氧化。
关键字: 阻燃镁合金；氧化膜；选择性氧化；第三元素效应
（1. College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China;
2. Key laboratory of Interface Science and Engineering in Advanced Materials, of Ministry of Education,
Taiyuan University of Technology, Taiyuan 030024, China）
Abstract:By adding Y and Ce high ignition-point temperature was realized in Mg-Y-Ce magnesium alloy, which can be melted in air without any protection. All the alloys, i.e., Mg-Y and Mg-Y-Ce alloys were prepared by adding commercial purity Mg (99.9%, mass fraction), Mg-25%Y (mass fraction) master alloy and pure Ce (99.5%, mass fraction) in a steel crucible under a cover gas mixture of CO2 and 0.5%SF6. AES (PHI550 ESCA/SAM) and XRD (X’Pert Pro MPD) analysis of the oxide scale reveals that, when the ignition-proof Mg-3Y-45Ce alloy is exposed in air at high temperature the oxidation film includes two layers. The outer layer consists of Y2O3, and the inner layer consists of Mg and MgO with a little Y and Ce. Based on the analysis of the high temperature oxidation thermodynamics, the model of the selective oxidation for Mg-Y alloys at high temperature was established, and the critical content of Y for the selective oxidation of Mg-Y alloys was obtained to be about 7% (mass fraction). The third element effect of Ce in the selective oxidation of Mg-Y alloys was analyzed. Ce plays a role of “getter” which inhibits the diffusion of O to internal alloy, so as to inhibit the inner oxidation of Y.
Key words: ignition-proof magnesium alloy; oxidation film; selective oxidation; the third element effect
