It was recalled that a new approach to the weak-beam technique, for the measurement of dissociated dislocation spacings and the evaluation of stacking-fault energies, had recently been proposed. The importance and utility, of using convergence values which were beyond those usually thought to be appropriate, had been demonstrated by means of image simulation. This new convergent weak-beam technique was here applied to the case of a g(4g) condition at 200kV. It was concluded that the reported effect of convergence in weak-beam transmission electron microscopy had been experimentally confirmed in the present case. Due to the fact that depth oscillations were smeared out, the accuracy of partial dislocation spacing measurements was increased when the beam convergence was increased. A further study of the effect of convergence showed that the higher the deviation parameter, the lower was the variation in average apparent spacing as a function of convergence.

Assessment of Convergence Effects in Weak-Beam Transmission Electron Microscopy in Partial Spacing Measurements in Ni3Al. Meng, X., Schäublin, R.E., Stobbs, W.M.: Philosophical Magazine Letters, 1997, 75[4], 179-85