Self-organization of cooperative grain boundary sliding in aluminium tricrystals

Abstract

Grain boundary sliding (GBS) being an important mechanism of high temperature deformation of polycrystals acquires a leading role in microcrystalline materials providing a superplasticity effect in them. Self-organization of change (increase) in angles of triple junctions providing CGBS realization was experimentally studied in a number of works. In particular, it was established that long range chains of grain boundaries are formed in structure of different materials. That is due to superplastic deformation. These chains are arranged almost in a straight line. Many well-known models on accommodation of GBS during superplastic deformation suggest the straightening of triple junctions. However, driving force and mechanisms of such transformation remain unclear in many cases. The aim of the present work is to design a transmission of GBS via a triple junction, to show physical origin of the triple junction transformation and to suggest a mechanism of the process. Well attested tricrystals are the best two dimensional model objects for such investigations.