Oxidation Resistance and Strength of TiAl Based Alloys in a Simulated

TiAl 基合金在模拟中的抗氧化性和强度

• 批准号: 12450295
• 负责人: TANIGUCHI Shigeji
• 金额: $ 8.96万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12450295/
• 关键词: titanium Aluminide; high temperature; Oxidation; Oxide seal; protectiveness; combustion atmosphere; 強度; TiO_2; Al_2O_3連続層; Ti_2AlN; 低A1濃度層; 水蒸気; Al_2O_3; TiN

The cyclic oxidation behavior of γ - TiAl based alloys, Ti-48Al-2Cr-2Nb, Ti-48Al-2Cr-2Fe, Ti-48Al-2Cr-2W and Ti-48Al-2Cr-1W-1Ta (mol %), was studied in a simulated combustion gas at 1173 K for up to 25 cycles (500 h). The oxidation products and subsurface areas were examined and characterized by using X-ray diffractometry, SEM and EPMA. All the alloys except Fe-containing one show excellent oxidation resistance for at least up to 25 cycles by forming thin and adherent oxide scals. In particular, the mass gains of W-containing alloys are a third of that of Ti-48Al-2Cr-2Nb, indicating significant effect of W. Ta seems to behave similarly as W. The excellent oxidation resistance is attributed to the formation of a definite and dense Al_2O_3 layer in the scale during the initial oxidation stage. A stable Al-depleted layer (so-called Z phase) is formed beneath the scale. The influence of Nb, Ta, and W seems to stabilize the Al-depleted layer in addition to the doping effect. However, their mass gains due to the oxidation are smaller than those tested in laboratory air, though the combustion gas was thought more aggressive than air. On the other hand, Ti-48Al-2Cr-2Fe oxidizes rapidly with scales consisting of two layers, an outer TiO_2 layer with heterogeneously distributed iron and chromium oxides and an inner porous layer which is a mixture of Al_2O_3 and TiO_2 grains.

研究了Ti-48 Al-2Cr-2Nb、Ti-48 Al-2Cr-2Fe、Ti-48 Al-2Cr-2 W和Ti-48 Al-2Cr-1 W-1 Ta（mol %）γ - TiAl基合金在1173 K模拟燃气中的循环氧化行为。用X射线衍射仪、扫描电镜和电子探针对氧化产物和亚表面进行了分析和表征。所有的合金，除了含铁的一个显示出优异的抗氧化性，至少高达25个循环，形成薄和粘附的氧化皮。特别是含W合金的增重是Ti-48 Al-2Cr-2Nb合金的三分之一，表明W的作用显著。Ta的行为似乎与W相似。氧化初期在氧化膜中形成了一层致密的Al_2O_3层，这是其抗氧化性能优良的原因。在氧化皮下形成稳定的贫Al层（所谓的Z相）。Nb、Ta和W的影响似乎除了掺杂效应之外还使Al耗尽层稳定。然而，尽管燃烧气体被认为比空气更具侵蚀性，但它们因氧化而产生的质量增量小于在实验室空气中测试的质量增量。Ti-48 Al-2Cr-2Fe合金氧化迅速，氧化膜由两层组成，外层为不均匀分布的铁、铬氧化物TiO_2，内层为Al_2O_3和TiO_2颗粒的混合物。