Development of microstructural observation technique for lessductile materials deformed in tension

低延性材料拉伸变形微观结构观察技术的发展

基本信息

批准号：
05650677
负责人：
HORITA Zenji
金额：
$ 1.41万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

项目摘要

In order to examine microstructural evolution with tensile deformation of less ductile materials such as intermetallics and ceramics, a modification has been made of double-shear testing technique which can be used as an simple application of a conventional bending test. Analytical electron microscopy (AEM) has been used to measure interdiffusion coefficients of Ni_3Al and Ni_3Ge which are important for the evaluation of mechanical properties at high temperatures. AEM has been further used to locate substitutional alloying elements in Ni_3Al, NiAl and TiAl. The results are summarized as follows.1. Double-shear specimens with 3 mm in diameter and 11 mm in length can give the same mechanical behavior as expected from conventional tensile specimens. It is then possible to examine tensile properties of less ductile materials with use of the double-shear testing technique.2. Interdiffusion coefficients of Ni_3Al and Ni_3Ge are repesented by an Arrhenius relation as D=D_0exp (-Q/RT) with D_0=1.18x10^<-4>m^2/s and Q=276 kJ/mol for Ni_3Al and D_0=9.03x10^<-5>m^2/s and Q=248 kJ/mol for Ni_3Ge.3. Substitutional alloying elements, Mn and Fe, which are effective to improve ductility of Ni_3Al, are located at both the Al and Ni sites in almost an equal maginitude. In this experiment, delocalization effects have been corrected using disordered phases, while the correction technique being developed by the authors.4. Alloying element, Fe, is more likely to occupy the Ni site in NiAl when alloyed with Ti with the preference of Al site, and to occupy the Al site when alloyed with Pd with the preference of Ni. In this experiment, the authors developed an equation which allows site occupancy determination in multi-component systems.5. Addition of Mn to TiAl reduces the strength of covalent bonding between Ti and Al and lowers the c/a to activate many slip systems so that, it has been suggested, the ductility of TiAl can be improved.

为了检查金属间化合物和陶瓷等延展性较差的材料在拉伸变形下的微观结构演变，对双剪切测试技术进行了修改，该技术可以用作传统弯曲测试的简单应用。分析电子显微镜（AEM）已用于测量Ni_3Al和Ni_3Ge的相互扩散系数，这对于评估高温机械性能非常重要。 AEM 已进一步用于定位 Ni_3Al、NiAl 和 TiAl 中的替代合金元素。研究结果如下： 1．直径为 3 毫米、长度为 11 毫米的双剪切试样可以提供与传统拉伸试样相同的机械性能。然后可以使用双剪切测试技术来检查延展性较差的材料的拉伸性能。2． Ni_3Al和Ni_3Ge的相互扩散系数用阿伦尼乌斯关系表示为D=D_0exp (-Q/RT)，其中D_0=1.18x10^<-4>m^2/s，对于Ni_3Al和D_0=9.03，Q=276 kJ/mol x10^<-5>m^2/s 且 Q=248 kJ/mol Ni_3Ge.3。有效提高Ni_3Al延展性的替代合金元素Mn和Fe以几乎相等的数量位于Al和Ni位点上。在本实验中，离域效应已使用无序相位进行了校正，而校正技术是由作者开发的。 4．当与Ti合金化并优先选择Al位时，合金元素Fe更有可能占据NiAl中的Ni位点，并且当与Pd合金化时优先占据Ni位点，更有可能占据Al位点。在这个实验中，作者开发了一个方程，可以确定多组件系统中的位点占用情况。5。在TiAl中添加Mn会降低Ti和Al之间的共价键强度并降低c/a以激活许多滑移系统，因此有人建议可以提高TiAl的延展性。