An X-ray diffraction line profile of cold-worked hexagonal alloys Zn-Ag: η and ε phase

Abstract

A detailed analysis of X-ray line broadening in filings of hexagonal zinc-silver alloys containing 0.9, 1.9 at. pct (η-phase) and 13.1, 16.8, 20.6, 24.6, and 28.8 at. pct Ag (e-phase) have been made using Warren and Averbach’s method of Fourier analysis. The diffraction profiles from fault-unaffected [H-K = 3N] reflections 10.0, 00.2, 11.0, 20.0, 11.2, 00.4 and fault-affected [H-K = 3N ± 1] reflections 10.1, 10.2, 10.3, 20.1, 20.2, 20.3 have been chart recorded in a Geiger counter X-ray diffractometer equipped with a LiF crystal monochromator. With an awareness of the small anisotropy in average domain size and strain, the deformation stacking fault probabilityα and growth fault probabilityβ have been calculated from a least-squares analysis performed on H-K = 3N ± 1 reflections. It has been observed that values ofα are significantly small while values ofβ are negligible — an observation remarkably different from hexagonal alloys studied earlier. The dislocation densityρ and the stacking fault energyγ have been evaluated for all the alloy compositions. Since the primary slip plane may be either basal or prismatic in hcp structures, a favorable slip mode in this system has been discussed on the basis of stacking fault energy and unit cell parameters.