The lattice spacings of certain primary solid solutions in silver and copper

Abstract

In continuation of previous work on valency effects in alloys, the present paper describes an investigation of the mean lattice spacings of primary solid solutions of cadmium, indium, tin, and antimony in silver, and of zinc, gallium, and germanium in copper. From these measurements the mean lattice distortions at equiatomic compositions are compared. The term “mean lattice distortion” is used here to denote the difference between the lattice constants of the solid solution and the solvent metal, as measured by the ordinary powder method of X-ray crystal analysis. It is well known that in solid solutions the X-ray methods give the mean lattice distortions, while more or less intensely localized regions of distortion may occur without preventing the formation of sharp diffraction lines. The present experimental data refer to the mean values only. 2-Experimental X-ray Technique —The lattice constants were determined from DebyeScherrer photographs obtained with a 9 cm. diameter camera of the type used by Bradley and Jay, in conjunction with a demountable X-ray tube made by the Metropolitan Vickers Electrical Co., Ltd., to whom the authors must express their thanks for instruction in manipulation. The powder specimens were made from filings which had passed through a 380 mesh sieve, and were mounted on a hair with Canada balsam. The camera contained a sliding window through which a thermocouple was inserted with its hot junction near to the specimen, and the temperature was controlled accurately by blowing a current of air round the camera.