EVALUATION OF Nb SOLID SOLUTIONS AS MATRIX OF COMPOSITES FOR VERY HIGH TEMPERATURE STRUCTURAL APPLICATIONS

评估铌固体溶液作为复合材料基体的超高温结构应用

基本信息

批准号：
08405045
负责人：
HANADA Shuji
金额：
$ 24.13万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08405045/
关键词：
niobium alloy very high temperature material composite strength

项目摘要

High temperature deformation behavior was investigated by using Nb solid solution single crystals in order to obtain fundamental data for development of Nb base in-situ composites for very high temperature structural applications. Nb-Ta and Nb-Mo alloys were se1ected to meet this objective, because Ta has a very small size misfit and shear modulus difference to Nb, while Mo has a significant size misfit and shear modulus difference to Nb. hi addition, both Ta and Mo have no scavenging effect in alloying with Nb, which means that the addition of these elements reveals the intrinsic nature of solid solution strengthening.Solid solution strengthening of Nb solid solutions, Nb-Ta and Nb-Mo, at low and intermediate temperatures can be interpreted in terms of size misfit and i-s (interstitial-substitutional) interaction. TEM observations indicate that deformation microstructures consist of long, straight screw dislocations, suggesting that screw dislocations interact strongly with Ta-O and Mo-O.This interaction is confirmed by the fact that marked anisotropy appears in the orientation dependence of yield stress and slip plane depending on oxygen content.At high temperatures yield stress of Nb-Ta-O decreases rapidly with increasing temperature, while that of Nb-Mo-O keep a high stress level up to about 1500K.Deformation microstructures of Nb-Mo-O at high temperatures consist dominantly of edge dislocations, suggesting the interaction of edge dislocations with Mo-O.Internal friction measurements reveal that at low and intermediate temperatures screw dislocations interact with Snoek atmosphere generated by Ta-O and Mo-O which receive the i-s effect, whereas at high temperatures edge dislocations interact with Cottrell atmosphere generated by Mo-O.

利用铌固溶体单晶研究高温变形行为，以获得开发用于超高温结构应用的铌基原位复合材料的基础数据。选择Nb-Ta和Nb-Mo合金来满足这一目标，因为Ta与Nb具有非常小的尺寸失配和剪切模量差异，而Mo与Nb具有显着的尺寸失配和剪切模量差异。此外，Ta和Mo在与Nb合金化时都没有清除作用，这意味着这些元素的添加揭示了固溶强化的本质。Nb固溶体、Nb-Ta和Nb-Mo的固溶强化，在低温和中温可以用尺寸失配和 i-s（间隙取代）相互作用来解释。 TEM观察表明，变形微观结构由长而直的螺型位错组成，这表明螺型位错与Ta-O和Mo-O强烈相互作用。屈服应力和滑移面的取向依赖性中出现显着的各向异性这一事实证实了这种相互作用。高温下，Nb-Ta-O的屈服应力随温度升高而迅速降低，而Nb-Mo-O的屈服应力在1500K左右仍保持较高的应力水平。高温下的 Nb-Mo-O 主要由刃位错组成，表明刃位错与 Mo-O 存在相互作用。内摩擦测量表明，在低温和中温下，螺旋位错与 Ta-O 和 Mo-O 产生的 Snoek 气氛相互作用其受到 i-s 效应，而在高温下，边缘位错与 Mo-O 产生的 Cottrell 气氛相互作用。