Dislocation damage by spark cutting in cadmium single crystals

Abstract

A method is described for estimating dislocation damage in crystals as a result of spark cutting. The method allows direct comparison of dislocation arrangement in the same area before and after cutting and is applied to estimate the maximum depth of damage (mdd) in cadmium single crystals using a dislocation etch on the (101bar above 0) plane.The investigation suggests that previous work on other metals has underestimated the mdd and in addition shows: The moving-wire cutter commonly used to section metal crystals frequently makes mechanical contact with the workpiece, with resultant shorting and mechanical abrasion.A simple fixed-wire cutter produces a more satisfactory and damage-free cut than the moving wire.Using this fixed wire, the mdd is a function of the diameter of the wire. Using the lowest available spark energy and a wire of 0·001 inch diameter, the maximum depth of damage in cadmium can be reduced to 0·1 mm.