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Influence of Alloying Elements on the oxidation Characteristics of Ti-Al Intermetallic Compounds

合金元素对Ti-Al金属间化合物氧化特性的影响

基本信息

批准号：
07650845
负责人：
TANIGUCHI Shigeji
金额：
$ 1.34万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07650845/
关键词：
titanium aluminide high temperature oxidation alloying element Al_2O_3 scale 金属間化合物

项目摘要

TiAl coupon specimens containing Hf of up to 5.2% were isothermally oxidised in a temperature range 1100 to 1400 K in a flow of purified oxygen under atmospheric pressure. The addition of 0.2% Hf is very effective to decrease the oxidation rate at 1200 and 1300 K.Metallographic examinations using the conventional methods revealed that the initially formed Al_2O_3 scale is maintained very sound by the addition. However, further additions of Hf result in a slight enhancement of oxidation at 1200 K and a gradual decrease of the effect at 1300 K.There is almost no effect by the addition of 5.2% Hf at 1300 K.The addition of 0.2% Zr is similarly effective as the addition of 0.2% Hf. These additives also improve the resistance to cyclic oxidation with temperature varying between room temperature and 1300 K for at least 100 cycle (360 ks). However, the effect of the both additives becomes small at 1350 K and at 1400 K it is inverted. Ti_3Al and Ti_3Al-21%Nb coupon specimens were isothermally oxidised in a temperature range 1100 to 1300 K in a flow of purified O_2, Ar-21%O_2 or N_2-21%O_2 under atmospheric pressure. The N_2 in the oxidation atmosphere decreases the oxidation rate of Ti_3Al a little. This is attributable to the formation of TiN resulting in the enrichment of Al near the specimen surface. A thin TiN layr is formed near the scale/Ti_3Al-21Nb substrate, leading to the enrichment of Al_2O_3 beneath the TiN layr and thus to a considerable decrease in the oxidation rate.

将含Hf高达5.2%的TiAl试样在1100 ~ 1400 K的温度范围内，在常压下的纯氧流中等温氧化。在1200和1300 K时，加入0.2% Hf对降低氧化速率非常有效。用常规方法进行金相检验表明，添加了Al_2O_3后，初始形成的Al_2O_3垢体保持良好。然而，进一步添加Hf导致在1200 K时氧化作用略有增强，而在1300 K时氧化作用逐渐减弱。在1300 K时加入5.2% Hf几乎没有影响。添加0.2% Zr与添加0.2% Hf同样有效。这些添加剂还提高了在室温和1300 K之间至少100个循环（360 ks）的温度变化下的抗循环氧化性。但在1350 K时，两种添加剂的影响都变小，而在1400 K时则相反。Ti_3Al和Ti_3Al-21% nb试样在1100 ~ 1300 K的温度范围内，在净化O_2、Ar-21%O_2或N_2-21%O_2的常压下进行等温氧化。氧化气氛中的N_2略微降低了Ti_3Al的氧化速率。这是由于TiN的形成导致试样表面附近Al的富集。在Ti_3Al-21Nb衬底附近形成了一层薄薄的TiN层，导致TiN层下的Al_2O_3富集，从而大大降低了氧化速率。