X-Ray Study of Faults in Body-Centered Cubic Metals

Abstract

The effect on the x‐ray diffraction pattern of deformation faults and twin faults occurring at random on the (211) planes of a b.c.c. lattice has been investigated. In single crystal reflections, deformation faults produce peak shifts and peak broadening, and twin faults produce a peak asymmetry and peak broadening. For a powder pattern it is necessary to average over the different components of a powder‐pattern peak; the peak shifts average out to zero, and the peak asymmetries to a quantity which is generally too small to measure. Both types of fault produce a line broadening which varies strongly from one powder peak to another. The hkl dependence of the broadening is the same for the two kinds of faults, and only a combination of the two probabilities can be measured. Measurements were made on samples of cold‐worked β‐brass filings in different states of annealing. There were no measurable peak shifts or peak asymmetries. The ratios of the effective particle size values could be explained only if a major part of the particle size broadening is due to faulting. The results are discussed in connection with measurements on other cold‐worked b.c.c. metals.