Behavior of Dislocations in Fe-3% Si under Stress

Abstract

Behavior of individual dislocations is investigated by stretching the foil single crystals of Fe-3% Si inside a 500 kV electron microscope. Formation of dislocation dipole trails and loops are continuously observed under the microscope, and is attributed to jogs caused by cross glide. Slip traces of individual dislocations are wavy even in the electron microscopic scale, but are nearly parallel to a low index plane. Dislocation activity is larger when the dislocation is moving in the outer part of a slip band, where the dislocations are less joggy. Evidences on mode of dislocation multiplication and interaction are obtained.
Drag stress by jogs as well as long range force between dislocations amounts only to a small fraction of the flow stress. Peierls mechanism can be used to explain consistently the elongated screw dislocations, the single ended dislocation sources and the large frictional stresses observed in this material.