W-Re合金热稳定性与高温抗氧化行为

Thermal Stability and High-Temperature Oxidation Behavior of W-Re Alloy

摘要:

高温合金在核聚变等领域的发展中有着十分重要的位置，为研究钨铼（W-3%Re）合金在高温下的稳定性能及抗氧化性能，将钨（W）及W-3%Re合金试样置于（500、700、900 ℃）高温环境下进行6 h的热稳定性实验；并在不同温度（700、800、900 ℃）下进行18 h的氧化实验。利用XRD、SEM、LSM800全自动3D形貌分析仪和Hysitron TI Premier纳米压痕仪等微尺度分析表征方法，分析氧化过程中氧化膜物相组成、氧化动力学规律、氧化产物及表面形貌、硬度等。结果表明，随着氧化时间的延长，合金质量随之增加；使得W-3%Re合金能更快地形成氧化膜，表面氧化层逐渐变厚，提高了W-3%Re合金的高温抗氧化性能。相比于W，W-3%Re合金中的氧化物化学稳定性更高，在700 ℃下恒温氧化18 h，表现出较低的氧化速率常数，此时的W-3%Re合金为弱抗氧化级，在氧化过程中氧化层的致密度得到一定提高。由此表明，Re元素的加入提高了材料W的高温抗氧化性能。

Abstract:

Superalloys have a very important position in the development of nuclear fusion and other fields. To study the stability and oxidation resistance of W-3%Re alloy at high temperature, the thermal stability experiments of W and W-3%Re alloy were conducted at the temperature of 500, 700, and 900 ℃ for 6 h. Oxidation experiments were conducted at the temperature of 700, 800, and 900 ℃ for 18 h. The phase composition, oxidation kinetics, oxidation products, and surface morphology of the oxide film were analyzed by XRD, SEM, LSM800 automatic 3D morphology analyzer, and Hysitron TI Premier nanoindentation apparatus. The results show that the quality of the alloy increases with the prolongation of oxidation time. During the oxidation process, the grain size of W-3%Re alloy is reduced, the oxidation film forms faster, the surface oxide layer is gradually thicker, and the high temperature oxidation resistance of W-3%Re alloy is improved. Compared with W, the chemical stability of the Re oxide in W-3%Re alloy is higher. And W-3%Re alloy shows a lower oxidation rate constant when it is oxidized at 700 ℃ for 18 h. At this time, the W-3%Re alloy is a weak oxidation grade, and the density of the oxide layer is improved to a certain extent during the oxidation process. This indicates that the addition of Re can improve the high temperature oxidation resistance of W material.