In situ studies of deformation at interfaces

Abstract

During the last twenty-five years there have been a number of studies of dislocation motion and interactions performed in the electron microscope. In general these observations have been limited by a number of technical shortcomings which have compromised their usefulness. In recent years, however, significant developments in the design and construction of specimen stages and in systems for recording in situ experiments in real time in the electron microscope have led to a renewed interest in dynamic experiments. One such application is the study of the interaction of dislocations with interfaces in polycrystalline solids, a topic which is of fundamental interest in understanding the laws which govern macroscopic deformation. It has been clearly demonstrated that in situ experiments are essential to this investigation, as they have provided direct observation of deformation mechanisms which conventional TEM analyses, in which the samples are deformed before they are put in the microscope, cannot. The two types of TEM observations provide complementary information, each greatly enhancing the value of the other.