MOVEMENT AND INTERACTIONS OF DISLOCATIONS IN NICKEL-CHROMIUM ALLOYS

Abstract

Interactions of dislocations, especially under dynamic conditions, on a single glide plane or from two crossing glide planes were studied in general, and certain dislocation configurations in particular, by means of transmission electron microscopy and diffraction contrast methods. The main findings are:1. Hexagonal dislocation networks are mainly formed by the interaction of dislocations on a single glide plane with Burgers vectors at 120°.2. Like screw dislocations, edge and mixed dislocations can also cross-slip between two glide planes.3. Interactions of dislocations from two crossing glide planes sometimes form long, straight, non-mobile dislocations at the intersections, e.g., Lomer-Cottrell dislocations. However, this non-mobile dislocation does not block, as it is generally accepted, the movement of dislocations on these two glide planes.4: In nickel-chromium alloys containing aluminum and titanium, interactions of superlattice dislocations are more or less similar to those observed in Al-and Ti-free alloys or in disordered solid solutions.