研究了微量Al、Ti元素对Inconel 690合金在850~1200℃下氧化行为的影响。结果表明，添加微量Al元素减小了Inconel 690合金在850~1200℃范围内的氧化增重，提高了合金的抗氧化性能。Al、Ti元素的复合添加提高了Inconel 690合金在850℃下的氧化速率。但在1000和1200℃下，该合金的平均氧化速率和氧化增重又均减小。添加微量Al元素后，晶界处形成的Al₂O₃颗粒阻碍了Cr³⁺的扩散，抑制Cr₂O₃膜的生长并减少合金内部孔洞的数量，从而提高氧化膜与基体的结合力，降低合金的氧化速率。当Al和Ti元素复合添加时，Ti⁴⁺在Cr₂O₃膜中作为高价离子掺杂，促进阳离子向外扩散，加快合金的氧化，导致合金在低温下的抗氧化性能略有下降。但Ti在氧化过程中倾向于向Cr₂O₃膜的表层偏聚，形成了不易挥发的富Ti氧化层，抑制高温下Cr₂O₃的挥发和剥落，提高合金在1000和1200℃下的抗氧化性能。

Inconel 690 alloy is a nickel-based alloy with a high chromium content that provides excellent oxidation and corrosion resistances. The high oxidation resistances of the alloy is attributed to the protective Cr₂O₃ that forms during oxidation, which prevents the outward diffusion of alloy elements and the inward diffusion of oxygen. However, when the temperature exceeds 1000^oC, the volatilization and spallation of the Cr₂O₃ oxide scale severely reduce the oxidation resistance of the Inconel 690 alloy. The addition of trace active elements is an effective way to improve the oxidation resistance of superalloys; however, the effects of these elements on the oxidation behavior and mechanism of the Inconel 690 alloy remain unclear. In this study, the oxidation behavior of Inconel 690 alloys with varying contents of Al and Ti elements was systematically studied through oxidation kinetics, morphology observation, and element analysis. In addition, the effects of Al, Ti, and their coadditions on the oxidation behavior and mechanism of the Inconel 690 alloy were investigated. The results indicate that the addition of Al reduces the oxidation mass gain and improves the oxidation resistance of the Inconel 690 alloy. Moreover, the addition of Al and Ti accelerates the oxidation rate of the alloy at 850^oC, but retards it at 1000 and 1200^oC. The positive influence of Al addition can be attributed to the fact that Al₂O₃ particles precipitated at the grain boundary hinder the diffusion of Cr³⁺ along the grain boundary. The slow diffusion of Cr³⁺ inhibits the growth of the Cr₂O₃ oxide scale and reduces the number of holes in the alloy. As a result, the oxidation resistance of the alloy increases owing to the decrease in the oxidation rate and the increase in adhesion between the oxide scale and the substrate. When Al and Ti are added, Ti⁴⁺ , which acts as a high-valence ion, is doped into the Cr₂O₃ scale, promoting the outward diffusion of Cr³⁺ and accelerating the oxidation rate of the alloy at lower temperatures (850^oC). However, during oxidation, Ti tends to converge toward the surface of the Cr₂O₃ scale and form a nonvolatile Ti-rich oxide layer. The formation of this layer inhibits the volatilization and peeling of Cr₂O₃, thereby increasing the oxidation resistance of the Inconel 690 alloy at 1000 and 1200^oC.