On the strainfree preparation of copper single crystal samples with low dislocation densities

Abstract

The chief purpose of this work is to report the successful development of strainfree preparation techniques that do not require the prehardening of the crystals by fast neutrons. Other methods of preparation are briefly reviewed. The special problems arising in handling faultless metal crystals are investigated. The delicate problem of holding thin samples has been overcome by using grease for mounting. A novel technique for making precision cuts without introducing lattice strains is described. The working principle is the superposition of immiscible fluids. It is possible to cut slices of only 05 mm thickness. Following the cutting process, the samples are flattened by a new electrolytical technique involving mechanical passivation of the sample, which is brought about by choosing a suitable electrolyte and by a superposed alternating current. In combining the cutting and flattening techniques it is possible to prepare crystal faces plane to within ±5 μm over a circular area of 9 mm diameter. The strainfree preparation is described of thin single crystal foils which are required for transmission x-ray investigation. By a special technique foils can be made less than 100 μm thick. Copper foils free of dislocations (8 mm diameter) have been prepared and investigated.