Brittle Fracture in Iridium Single Crystals

Abstract

A study of the brittle fracture of iridium is made using the scanning electron microscope. Except where macroscopic imperfections are present, cracks can only be nucleated after extensive work-hardening. Plastic relaxation of the crack is inhibited because impurities substantially increase the critical resolved shear stress. Brittle fracture in iridium is thus basically an impurity effect.