Quantitative analysis of electron channeling contrast of dislocations

Abstract

Quantitative analysis was performed for electron channeling contrast (ECC) of dislocations in a [001] single-crystal 316 L stainless steel sample in order to establish the range of deviation parameter, w, for optimal dislocation imaging. Channeling contrast was evaluated from a series of ECC images taken as a function of sample tilt at ∼ 0.1° increments across 〈200〉 Kikuchi lines. The deviation parameter, w, was estimated by quantitative analysis of several parameters, namely experimental dislocation contrast intensity and dislocation feature width, as well as calculated BSE signal. Our analysis reveals that optimum dislocation imaging conditions by ECC occur for positive values of w. Under these imaging conditions, dislocations displayed strong contrast and narrow dislocation feature width, y. In particular, we found that the value of y can be greatly reduced (about two times in the present work) by using large positive values of w (w > 1.0 ± 0.5). Out of these channeling conditions, dislocations displayed weak contrast and larger y-values were measured.