Abstract
This chapter discusses the geometry of dislocation glide in L1 2 γ´-phase. It emphasizes the geometry of dislocation glide in L1 2 alloys on three scales: (1) the shape of the spreading dislocations on a scale of microns or more, (2) the gross dissociation into APB- or SISF-separated superpartials on a scale of nanometers, and (3) the fine dissociation into partials of the parent f.c.c, lattice on a scale of angstroms. The chapter presents transmission electron microscopy (TEM) observations of dislocations and other related defects that characterize these two contrasting slip modes in γ´ and, on this basis, describes the controlling dislocation mechanisms. When the temperature exceeds about 800°C, the slip direction changes to (100), the shortest lattice translation vector in L1 2 ; the origin for this transition is described in the chapter. It was using a transmission electron microscope that Marcinkowski, Brown, and Fisher obtained the first direct experimental evidence for an important hypothesis, proposed almost half a century ago by Koehler and Seitz, about dislocations in superlattice structures: the dislocations would propagate more readily if they existed in groups coupled by antiphase boundaries (APB).
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
