界面残余应变场的会聚束电子衍射测定(英文)

Residual strain fields determined at composite interface using convergent beam electron diffraction

用两种会聚束电子衍射 (CBED)技术研究了复合材料界面残余应变场。常规正焦CBED方法中 ,用优化算法使计算的高阶Laue带 (HOLZ)线图与实验图达到最佳拟合 ,进而确定残余应变。给出了一种减少优化计算中可调参数数目的方法。残余应变与表面弛豫引起的界面附近点阵平面面间距的变化、点阵平面的旋转与弯曲使得离焦的大角度会聚束电子衍射(LACBED)图中的衍射线移位、分裂与弯曲。表面弛豫引起的点阵平面的旋转也决定于本征应变。通过使动力学理论计算的LACBED图与实验图达最佳拟合 ,可以确定本征应变。用该方法研究了颗粒增强复合材料Al2 O3 Al与晶须增强复合材料(K2 O·6TiO2 )w

The residual strain fields at composites interface were studied with two convergent beam electron diffraction (CBED) techniques. One technique is conventional in focus CBED, in which the residual strains were determined by using optimization algorithms to fit the calculated higher order Laue zone (HOLZ) line patterns with experimental ones. A method for optimization of the adjustable parameters was proposed. Another technique is defocus large angle CBED (LACBED), in which the diffraction lines near the interface became shifted, split and twisted, because near the interface the lattice plane spacings are changed and planes are rotated and bent due to residual stresses and surface relaxation. Local lattice plane rotations due to surface relaxation are also dependent on the eigenstrain. By fitting the experimental LACBED pattern with the pattern calculated using dynamical theory, the eigenstrain was determined. These techniques were applied to measure interfacial strain fields in particle reinforced composite Al 2O 3/Al and whisker reinforced composite (K 2O·6TiO 2) w/Al.