Ti—Al—Nb系金属间化合物基合金的抗氧化性能研究

本文研究了 Ti-Al-Nb 系中广泛成分范围里的金属间化合物基合金在900—1200℃等温静态氧化时的抗氧化性能.研究结果表明,合金的 Al 含量以及 Ti 和 Nb 的原子比影响合金的抗氧化性能.Al 提高合金的氧化抗力,而过高或过低的 Ti 和 Nb 的原子比都显著地降低合金的氧化抗力.用 X 射线衍射法测定了氧化膜的组成,指出具有完整的 Al_2O_3保护膜是这类合金具有优良的抗氧化性能的基本条件.提出了 Ti-Al-Nb 系中具有优良抗氧化性能合金的成分范围.在所得到的氧化图上清楚地显示了氧化水平、氧化膜的组成、氧化温度及合金成分之间的关系.研究了两个典型合金的氧化动力学曲线,并讨论了氧化机理.

OXIDATION RESISTANCE OF INTERMETALLICS-BASE ALLOYS IN Ti-Al-Nb TERNARY SYSTEM

The isothermal oxidation resistance of intermetallics-base alloys with a wide range of composition in the Ti-Al-Nb ternary system under the tempera- ture range from 900 to 1200 C has been studied in this paper.Results indicate that the factors like AI content and the atomic ratio between Ti and Nb affect the oxi- dation resistance of the alloys.Al can improve the oxidation resistance,while the atomic ratio between Ti-and Nb,too high or too low,will reduce the oxidation resistance dramatically.The composition of the oxide film was determined by X-ray diffraction. It is pointed out that the integrated protective Al_2O_3 film is the basic condition for good oxidation resistance of the alloys.A composition range of the alloys with good oxidation has been proposed.The oxidation level,the composition of the oxide film,the oxidative temperature and the relation between constituents of the alloy are clearly shown on the diagram.Oxidation kinetic curves of two typical alloys are stu- died and the oxidation mechanism is discussed.