Stress and Temperature Dependence of High Temperature Creep Resistance in Intermetallic Compound TiAl

金属间化合物 TiAl 的高温抗蠕变性的应力和温度依赖性

基本信息

批准号：
04650644
负责人：
KIKUCHI Makoto
金额：
$ 1.28万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04650644/
关键词：
INTERMETALLIC COMPOUND Ti-50Al CREEP CURVE STRESS ECPONENT OF MINIMUM CREEP RATE ACTIVATION ENERGY FOR CREEP DYNAMIC RECRYSTALIZATION MINIMU CREEP RATE SUBGRAIN 転位下部組織活性化エネルギークリープ最小クリープ速度の応力指数

项目摘要

Constant creep tests in the stress range of 100 to 300 MPa were conducted at 1123 K using the full size specimens of Ti-50 at% Al heat treated at 1473 K for 6*10^5s. The stress dependence of the stress exponent of the minimum creep rate, called as n value, were investigated. The specimens crept at certain stress levels were interrupted at the time showing the minimum creep rate. The stress dependence of the dislocation substructures subjected to creep deformation were examined using the transmission electron microscopy. Following conclusions were reached.1)The creep curves of TiAl exhibited no steady state stage. Thus, they consist of a transient stage and an accelerating creep stage. The latter occupied more than 90 pct of the rupture life.2)The stress exponent of the minimum creep rate, n value, remains constant and equals to 3 less than 150MPa. In the stress range of 150 to 300 MPa, n value increase up to 8 with increasing the stress levels.3)Under the stresses of less than 150 MPa, dynamically recrystalized grains can not be observed at the minimum creep rate stage. In the stress range of 150 to 300 MPa, however, dynamically recrystalized grains form along the grain boundaries.4)linear increase of internal stress is obtained up to 150 MPa, so the ratio of the internal stress to the applied stress, sigma_i/sigma_a, remains constant value of 0.9. Under the stress of more than 150 MPa, sigma_i/sigma_a decreases with increasing the applied stress.

使用在 1473 K 下热处理 6*10^5s 的 Ti-50 at% Al 全尺寸试样，在 1123 K 下进行了 100 至 300 MPa 应力范围内的恒定蠕变试验。研究了最小蠕变速率的应力指数（称为 n 值）的应力依赖性。样品在一定应力水平下蠕变，在显示最小蠕变速率时被中断。使用透射电子显微镜检查了蠕变变形下位错亚结构的应力依赖性。得出以下结论：1)TiAl的蠕变曲线没有表现出稳态阶段。因此，它们由瞬态阶段和加速蠕变阶段组成。后者占断裂寿命的90％以上。2）最小蠕变速率的应力指数n值保持不变，小于150MPa时等于3。在150～300 MPa的应力范围内，随着应力水平的增加，n值增加到8。3）在小于150 MPa的应力下，在最小蠕变速率阶段观察不到动态再结晶晶粒。然而，在 150 至 300 MPa 的应力范围内，沿晶界形成动态再结晶晶粒。4) 内应力线性增加直至 150 MPa，因此内应力与外加应力之比 sigma_i/sigma_a ，保持恒定值 0.9。在超过150 MPa的应力下，sigma_i/sigma_a随着施加应力的增加而减小。