X-ray diffraction analysis of stacking and twin faults in f.c.c. metals: arevision and allowance for texture and non-uniform fault probabilities

A revision is presented of the original description by Warren [X-ray Diffra ction, (1969), pp. 275-298. Massachusetts: Addison-Wesley] of the intensity distribution of powder-pattern reflections from f.c.c. metal samples conta ining stacking and twin faults. The assumptions (in many cases unrealistic) that fault probabilities need to be very small and equal for all fault pla nes and that the crystallites in the sample have to be randomly oriented ha ve been removed. To elucidate the theory, a number of examples are given, s howing how stacking and twin faults change the shape and position of diffra ction peaks. It is seen that significant errors may arise from Warren's ass umptions, especially in the peak maximum shift. Furthermore, it is explaine d how to describe powder-pattern reflections from textured specimens and sp ecimens with non-uniform fault probabilities. Finally, it is discussed how stacking- and twin-fault probabilities (and crystallite sizes) can be deter mined from diffraction line-profile measurements. (C) 2000 International Un ion of Crystallography Printed in Great Britain - all rights reserved.