In order to investigate grain boundary structures, and the effect of impurities upon the microstructure, bi-crystals with various boundaries were prepared, <001>(1¯30)  = 5, <001>(1¯20)  = 5, <001>(1¯40)  = 17, <001>(1¯50)  = 13, <110>(3¯32)  = 11, and their structures were studied by using transmission electron microscopy. In the case of pure specimens, periodic structures were observed which could be explained in terms of geometrical models (coincidence site lattice, O-lattice) for the periodicity and in terms of molecular dynamics calculations for the microstructures. It was found that the grain boundary structures consisted of combinations of structural units of stable boundary: (0¯10) and (1¯10)  = 1 single crystals, and (1¯30)  = 5 coincidence boundary. In the case of impure specimens, precipitates and lattice bending were observed at the boundaries. It was concluded that impurities were one of the most important factors which affected the boundary structure in this metal. On the other hand, the effect was very different for each boundary.

K.Morita, M.Uehara, S.Tsurekawa, H.Nakashima: Journal of the Japan Institute of Metals, 1997, 61[4], 251-60