Interferometric Observations of Yield in Thallium Bromo-Iodide

Plastic flow has been determined quantitatively in a thallium-bromo-iodide (KRS-5) crystal as a function of applied force and loading time. A microinterferometric technique was employed to examine the depth and contours of depressions formed by statically loaded steel spheres and the elastic recovery of the material. An unusual geometric pattern was formed around a small percentage of the load regions, the nature of which suggested slip line formation in the cubic crystal lattice.