An X-Ray Study on the Micro Strain and the Coherently Diffracting Domain Size in Electrodeposited Chromium

Abstract

It is recognized that electrodeposits are similar in microstructure to the microcrystals produced by cold work and the crystals with high internal stress and preferred orientation.In order to obtain the knowledge of microstructures in chromium, electrodeposited from a chromic acid plating bath as a function of bath temperature, the X-ray diffraction line profiles of its deposits were analysed by Fourier series method which was practicable by using a single reflection only. The information on micro strain, coherently diffracting domain size was obtained from the Fourier cosine coefficients. Moreover, the effect of unresolved Kα line profile and Kα1 line profile separated by Rachinger's graphical method on the r.m.s. strain and the domain size were examined. From the experimental results, the following conclusions have been derived.(1) The value of r.m.s. strain obtained by using unresolved Kα line profile is a little larger than that in the case of Kα1 diffraction line profile separated by Rachinger's graphical method, but the domain she is slightly small in the case where unresolved Kα line profile was used.(2) It is found that the r.m.s. strains in electrodeposited chromium analysed on the (211) diffraction line profiles have decreased with increasing bath temperatures, in the range of 40 to 70°C, and again increased at 75°C. The influence of bath temperature on the stored energy and the dislocation density derived from the mean squared strain show a similar tendency as the r.m.s. strain. The coherently diffracting domain size in electrodeposited chromium on the (211) diffraction line profile has increased with increasing bath temperature, in the range of 40 to 70°C, and again decreased at 75°C.(3) The reflecting plane dependence of the r.m.s. strain and the domain size in electrodeposited chromium obtained from bath temperature of 60°C have been investigated on the three planes of (110), (200) and (211). It is found that the r.m.s. strain has increased in the order (200), (211), (110) and the domain siza in (211) plane is smaller than that in the case of (110) and (200) planes, but between the domain size in (110) and (200) planes, no marked difference has been recognized.