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Unified interpritation of high temperature crecp in an inclusion bearing material

夹杂物轴承材料中高温蠕变的统一解释

基本信息

批准号：
11450264
负责人：
SATO Eiichi
金额：
$ 3.39万
依托单位：
The Institute of Space and Astronautical Science
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

A steady-state creep model of a metal matrix composite was proposed considering the accommodation processes of the misfit strain between the matrix and reinforcements in order to comprehensively explain dispersion strengthening, composite strengthening and composite weakening. The proposed model was verified experimentally using the model composites, Ti/TiB in situ composites of 5, 15 and 20vol.%TiB, which have a good interfacial bonding, suitable size and aspect ratio of TiB for a moderate diffusional accommodation rate, and no fine oxides. A sigmoidal curve in a double-logarithmic scale of stress and strain rate was observed in the creep of Ti/15TiB at 1123 K and was classified into a complete-diffusional-accommodation region corresponding to composite weakening, a diffusional-accommodation controlled region and a plastic-accommodation-controlled region corresponding to composite strengthening with increasing stress. The activation energies in the three regions were close to those of the volume, interface and volume diffusion of Ti, respectively. In the plastic-accommodation-controlled region, the strain rate decreased with increasing volume fraction, while near the complete-diffusional-accommodation region, the strain rate scarcely changed. The strain rate of the transverse creep was ten times that of the longitude creep in the plastic-accommodation-controlled region, while the difference was scarcely observed near the complete-diffusional-accommodation region.

为了综合解释弥散强化、复合强化和复合弱化，考虑了基体与增强体之间失配应变的调节过程，建立了金属基复合材料的稳态蠕变模型。用5、15和20Vol.%TiB的原位复合材料进行了实验验证，该复合材料界面结合良好，TiB的尺寸和长径比适中，扩散调节速率适中，并且没有细小的氧化物。在1123K下，Ti/15TiB的蠕变曲线在应力和应变速率的双对数范围内呈S型曲线，并被划分为对应于复合弱化的完全扩散调节区域、对应于复合强化的扩散调节控制区和对应于复合强化的塑性调节控制区域。三个区域的激活能分别接近于钛的体积激活能、界面激活能和体积扩散激活能。在塑性调节控制区，应变率随体积分数的增加而降低，而在完全扩散调节区附近，应变率变化不大。在塑性调节控制区，横向蠕变的应变率是纵向蠕变的10倍，而在完全扩散调节区附近几乎没有观察到这种差异。