论文部分内容阅读
层错能(γ)是奥氏体合金的一个重要性能,对于Ni基高温合金,γ值的大小直接影响合金的高温性能,故准确测定γ值,对合金的成分设计具有指导意义。过去测定γ值多采用x光法或位错结点法但这两种方法都具有局限性,前者不能用于双相合金,而后者的准确度较差。本文利用弱束技术,研究了不同含Co量的γ—γ′双相合金U—700的层错能,其方法是利用弱束成象的高分辨率,(～1nm),在EM400T电镜上获得两条分开的偏位错象(见图1)。准确的测定这两条位错的间距(测量误差在±7A范围之内)。然后用各向异弹性理论导出的层错能公式:
The layer fault energy (γ) is an important property of austenitic alloys. For the Ni-based superalloy, the value of γ directly affects the high-temperature properties of the alloy. Therefore, the γ value is accurately determined, which is of guiding significance for the alloy composition design. In the past the determination of γ value using x-ray method or dislocation node method but both have limitations, the former can not be used for two-phase alloy, while the latter the accuracy is poor. In this paper, the weak-beam technique was used to study the stacking fault energy of γ-γ ’dual-phase alloy U-700 with different amounts of Co by using the high-resolution weak beam imaging (~ 1nm) Two separate offset images are obtained (see Figure 1). Accurate determination of the spacing between these two dislocations (measurement error within ± 7A). Then using the anisotropy theory derived layer fault energy formula: