Plastic Deformation in the Neck of a-Fe Single Crystals Leading to Fracture

Abstract : Single crystal iron whiskers have been grown by the reduction of ferrous halides by hydrogen. These crystals have been strained to fracture at various elongation rates at room temperature. Based on stress-strain data, observations of the glide geometry by scanning electron microscopy, and by the x-ray precession method, various deformation modes have been characterized. We observe that the geometry of the reduction in area is a predictable property of a particular orientation. The hardening rates as well as the reduction in area is found to be dependent upon the number of active slip systems. This, in combination with the results of the precession method provide us with a complete description of the deformation history of these crystals preceding fracture.