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观察了面心立方镍基合金中重叠微孪晶界面的各种条纹象,发现它们与α条纹及σ条纹不同,当改变基体或孪晶偏离参量的正负号时,重叠区域条纹的衬度会发生明显的改变,本文将多束动力学衍射理论的叠代法用于重叠孪晶界面几种条纹强度的模拟计算,计算束数包括基体、孪晶及其二次衍射在内共九束,计算的强度曲线与实验强度曲线符合良好,分析结果指出,重叠孪晶界面条纹衬度的明显变化是异常吸收或异常透射效应及基体-孪晶-基体三层晶体多束动力学交互作用的结果。Fringe images of overlapping micro-twin boundaries in a f.c.c. Ni-Cr alloy have been observed by trausmission electron microscopy. It is shown that the average intensity of the fringe images in the overlapping boundary is either much higher or much lower than that of the single boundary depending on the sign and value of the deviation parameters. The contrast of fringes will reverse when one changes the sign of deviation parameters for the matrix and/or the twin. Comparing with the well-known α-fringe and δ-fringe, overlapping twin fringes have special features which may arise from the anomalous absorption-anomalous transmission effects and the dynamic multiple beam interference among the matrix-twin-matrix or twin-matrix-twin. Using Van Dyck's iterative method, simulation images were calculated which are in good agreement with experimental observations.
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