Determination of Habit Planes Using Trace Widths in TEM

A simple and accurate method of determining the habit planes from the determination of beam and habit plane trace directions using Kikuchi line diffraction patterns and the measurement of the thickness of the thin foil has been developed. The thickness of the thin foil can be calculated from the measurements of the widths of the habit plane trace at two different positions. The first orientation is with the foil normal to the electron beam (zero tilt) and the second one is where the foil has been tilted by a known amount about an axis parallel to the original trace at zero tilt. From the beam and the trace directions and thickness of the thin foil, the indices of the habit plane normal may be calculated. The technique has been tested using {111} annealing twin interfaces in stainless steel and shown to be capable of determining habit planes to within a degree or two. Extension of this method to the measurement of martensite habit planes is described.