TWINNING AND INTERFACIAL PLANES IN COPPER

This work reports the distribution of a large, representative sample p opulation of grain boundary plane crystallography in pure, annealed co pper by use of an improved experimental procedure. The new methodology reduces the laboriousness and improves the accuracy of data collectio n, and so is described in detail. Analysis of the results concentrates on the Sigma 3 boundaries, and shows that three-quarters of these wer e tilt boundaries on the 011 zone. Of these tilt boundaries, nearly ha lf were coherent twins, i.e., on 111/111 planes, or near coherent twin s on 23,17,17/775 planes. The high population of the second group is t hought to be due to oxygen take-up during annealing. The data in gener al showed a trend for lower energy Sigma 3s to occur more frequently. The results were interpreted in terms of boundary energies, local equi libration, and comparisons with previous work in copper and other syst ems.