Dislocation studies on deformed single crystals of high-purity iron using positron annihilation: determination of dislocation densities

A new method for determining the total number of dislocations/unit area, and the fraction of screw and edge components, is presented. Single-crystal specimens which have been (a) bent over a mandrel, (b) cold rolled at room temperature, and (c) deformed in tension at 200K have been studied. Etch pits were studied in connection with this work and were found to be primarily of the < 111 > type. The density of emergent dislocations as determined by the etch pits was found to be smaller than the number determined by the positron-annihilation technique. 58 ref.--AA