FCC金属孪晶的EBSD分析

Analysis on the twinning of FCC metals by EBSD

电子背散射衍射技术常采用旋转角/旋转轴的形式来描述晶体中的孪生特征,而一般描述孪生特征的方法是采用孪晶面/孪晶方向的形式。依据孪晶的晶体学原理,推导出了两种描述形式之间的转换方法。针对面心立方金属的4种{111}<112>孪晶变体,基于上述两种方法获得了4种孪晶变体的两种表达形式,并建立了不同表达形式之间的对应关系。根据该对应关系可知,采用EBSD技术可确定面心立方金属中具体某一变体的孪晶面和孪晶方向。最后,基于EBSD技术的测试结果,采用所得对应关系分析了GH690和GH145两种镍基高温合金的孪晶变体,分析结果表明,4个60°<111>孪晶变体通常在变形中全部启动。

The twinning characteristic of crystal was described by the electron backscatter diffraction （EBSD） technology by the way of ro- tation angle combined with rotation axis. In general research, it was described by the way of twinning plane combined with twinning direc- tion. Based on crystallographic theory of twinning, the conversion method between the two description ways mentioned above was de- duced. For the four { 111 } 〈 112 〉 twinning variants of face-centered cubic （FCC） metals, two description forms were obtained, and the corresponding relationship between the two description ways was built. The relationship shows that the twinning plane and twinning direc- tion of a specific variant of FCC metals can be determined by EBSD. At last, based on measured results of EBSD, the twinning variants of GH690 and GH145 Ni based superalloys were analyzed by the above relationship. Analysis results show that all the four 60° 〈 111 〉 twin variants usually activate during the deformation.