Stress measurement diffractometer method

Until about 1950, x-ray stress measurements were made only by photographic methods. Today the diffractometer is preferred because it is faster and more precise. The photographic method, which still has its place, will be described later. 

Essentially, the quantity measured in the diffractometer method is A20 = (20 — 20j), the shift in diffraction-line position due to stress as the angle if/ is... 

This method of stress measurement is not often used today, because it is slower and less precise than the diffractometer method. However, the photographic method still has some advantages. The required apparatus is very simple a small back-reflection camera fixed to the head of a shockproof x-ray tube energized through a shockproof cable. This apparatus is smaller, lighter, more robust, and much cheaper than a mobile diffractometer. It is also more mobile and better suited to work in a confined space. 

G.39 Harold P. Klug and Leroy E. Alexander. X-Ray Diffraction Procedures, 2nd ed. (New York Wiley, 1974). Contains a great deal of useful detail on the theory and operation of powder cameras and diffractometers. Covers the following topics in depth chemical analysis by diffraction, parameter measurement, line-broadening analysis, texture determination, stress measurement, and studies of amorphous materials. Single-crystal methods are not included. 

---