X-ray diffraction and computer simulation studies of the structure of [001] twist boundaries in AuAg alloys

Abstract

A combined X-ray diffraction and Monte Carlo simulation study of the structure of Σ 13 [001] twist boundaries in gold-silver alloys, as a function of silver concentration is presented. Five alloy concentrations corresponding to 0, 25, 50, 75, and 100 at.% silver are studied. For the 50% alloy, a large number of absolute grain boundary structure factors are measured, both in the plane of the grain boundary and normal to it. At the other compositions fewer structure factors are measured. However, their magnitudes are found to be useful in setting limits on the extent of interfacial segregation. Generally good agreement is found between all measurements and calculations. For the 50% alloy it is concluded that the alloying with silver produces only very slight boundary segregation and changes in the positions of the substitutional sites in the boundaries (relative to that in pure gold) and that the gold and silver atoms are distributed on these sites almost randomly. Detailed information on atomic vibrations and individual site occupation probabilities is presented. © 1994.