انتقال بین مرزدانه با زاویه کم و زیاد

Transition between low and high angle grain boundaries 

انتقال بین مرزدانه با زاویه کم و زیاد 

ABSTRACT

The migration of planar, symmetric tilt grain boundaries with different tilt axes was investigated. The driving force for the grain boundary migration was due to an external mechanical stress field. Low as well as high angle grain boundaries can move under this driving force and the activation parameters for the stress induced grain boundary motion are different for low and high angle grain boundaries. The experiments showed a sharp transition from low angle grain boundary to high angle grain boundary behavior. The transition is marked by a clear change in the activation enthalpy for the grain boundary motion without any extended range. We present an overview of the existing experimental results and theoretical considerations of the structure of grain boundaries at the transition. The observation that the transition depends on the rotation axis of the grain boundary and on the grain boundary plane is particularly important, because this will influence the Brandon criterion which is often used in experiments and simulations of grain growth and recrystallization processes. 

 

ساختار مرزدانه‌های زاویه - باز The structure of high-angle grain boundaries

The structure of high-angle grain boundaries

ساختار مرزدانه‌های زاویه - باز

ABSTRACT

A coincidence model of high-angle grain boundaries can be extended to include deviations from coincidence. The generalised boundary has a terraced structure, corresponding to the densely packed planes in the coincidence lattice, and a superimposed dislocation network, corresponding to a sub-boundary in the coincidence lattice. This model is a natural extension of previous dislocation models and models based on coincidence relationships. The model explains many of the observed properties of grain boundaries and should have wide validity for the cubic system.