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采用恒温氧化增重方法,在静态空气中研究了Ti2Al Nb基合金轧板在650,700,750和800℃保温100 h条件下的高温抗氧化性能。利用扫描电子显微镜(SEM)、能谱仪(EDS)和X射线衍射(XRD)技术分析了氧化表面、截面形貌、元素分布以及物相。Ti2Al Nb基合金轧板,在650℃下未见明显的氧化层、700℃时氧化层厚度极小、800℃时氧化层厚度急剧增加。研究结果表明,在温度低于700℃条件下,氧化增重小于1 mg·cm-2,属于完全抗氧化级别。在750℃条件下,氧化增重明显,出现氧化分层,达到抗氧化级别。随着温度的升高,在800℃时有明显的氧化分层现象,但未形成连续致密的氧化层,氧化层出现明显孔洞。氧化产物主要为棱柱状的Ti O2相、层片状的Al Nb O4相和针状相。温度越高,分层越明显,富氧层越厚,危害性氧化物越多,氧化加剧趋势越明显。
The high temperature oxidation resistance of Ti2Al Nb-based alloy rolled plates at 650, 700, 750 and 800 ℃ for 100 h in static air was studied by the method of constant temperature oxidation and weight gain. The surface, cross section morphology, elemental distribution and phase were analyzed by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD) Ti2Al Nb-based alloy rolled plate, no obvious oxide layer at 650 ℃, the thickness of the oxide layer is very small at 700 ℃, the thickness of the oxide layer increases sharply at 800 ℃. The results show that under the condition of the temperature lower than 700 ℃, the weight gain of oxidation is less than 1 mg · cm-2, which belongs to the level of complete oxidation resistance. Under the conditions of 750 ℃, oxidation weight gain significantly, the emergence of oxidation stratification, to achieve antioxidant levels. With the increase of temperature, obvious oxidation stratification occurred at 800 ℃, but there was no continuous and dense oxide layer, and the oxide layer showed obvious pores. The oxidation products are mainly prismatic Ti O2 phase, lamellar Al Nb O4 phase and acicular phase. The higher the temperature, the more obvious stratification, the thicker the oxygen-rich layer, the more harmful oxides, the more obvious the trend of oxidation.