The structure of γ-brass

Abstract

Westgren and Phragmén have recently described the results of investigations on the structures of Cu-Zn, Ag-Zn and Au-Zn alloys. As a result X-ray analysis by the powder method, five different types of structure were found in the case of the Cu-Zn alloys. Structures were successfully assigned to four of these phases, but in the case of the γ-phase a complete elucidation was not attempted. The structure is cubic, and contains 52 atoms to the unit cube. The following table is taken from Westgren and Phragmén's paper:- Further information was obtained from examination of single crystals of a γ Cu-Zn alloy. Laue photograms and rotation photograms were both used for this purpose. By way of conjecture, Westgren and Phragmén suggested the formulæ Cu 4 Zn 9 , Ag 4 Zn 9 , abd Au 4 Zn 9 , as these correspond to compositions coinciding with one of the homogeneous γ-phase ranges. We have found that these formulæ are incorrect, the true formulæ being Cu 5 Zn 8 , Ag 5 Zn 8 , and Au 5 Zn 8 .