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采用静态增重法测定了GH4720Li合金在650~900℃的氧化动力学,并利用SEM、EDS和XRD手段分析了不同温度下氧化膜的组成及结构,据此对GH4720Li合金的氧化机制进行了研究。结果表明,GH4720Li合金在900℃以下属完全抗氧化级。750℃以下,GH4720Li合金的氧化速率随温度升高缓慢增加,氧化膜主要由(Cr0.88Ti0.12)2O3和Cr2Ni O4组成;超过750℃,合金的氧化速率显著增加,氧化层主要由(Cr0.88Ti0.12)2O3和Ti O2组成。Ti的含量沿氧化层厚度方向由里向外逐渐增加,而Cr的分布规律正好相反。合金氧化动力学遵循抛物线规律,氧化机制由初始表面生成反应控制转变为扩散机制控制。
The oxidation kinetics of GH4720Li alloy at 650-900 ℃ was measured by static weight method. The composition and structure of the oxide film at different temperatures were analyzed by SEM, EDS and XRD. The oxidation mechanism of GH4720Li alloy was studied . The results show that, GH4720Li alloy at 900 ℃ under the complete anti-oxidation grade. The oxidation rate of GH4720Li alloy increases slowly with the increase of temperature at 750 ℃. The oxide film mainly consists of (Cr0.88Ti0.12) 2O3 and Cr2NiO4. When the temperature exceeds 750 ℃, the oxidation rate of the alloy increases significantly, and the oxide layer mainly consists of (Cr0 .88Ti0.12) 2O3 and Ti O2 composition. The content of Ti gradually increases from the inside to the outside along the thickness of the oxide layer, while the distribution of Cr is the opposite. The oxidation kinetics of the alloy follows the parabolic law, and the oxidation mechanism changes from the control of initial surface formation reaction to the diffusion mechanism.