Crystallography of the ζ to β′ massive transformation in Ag-50 at.% Cd

Abstract

The orientation relationship between massive β′ precipitates and the large grained ζ phase Ag-50 at.% Cd containing them were determined by the Laue method, and the orientation of planar interphase boundaries between the parent and product phases were determined by two-surface trace analyses. Computer assisted analysis of the orientation relationships demonstrated that many of them had recognizable low index orientation relationships with their matrix grains. All of the precipitates had orientation relationships which could be characterized in terms of nearly parallel low index planes and directions, but many of these orientation relationships were observed only once, and these may not have mechanistic significance. A total of 37 planar interphase boundaries were examined by two surface trace analysis and their orientations compared with low index lattice planes in both the parent and product phases. Few of the planar interfaces corresponded to low index lattice planes in either the parent or the product phases, and only one planar boundary corresponded to low index planes of both phases. These results show that the mechanism of massive transformations is more complex than has been previously assumed.