Triple Junction Controlled Grain Growth

Grain growth in 2D polycrystals was simulated under the supposition that triple junctions possess a restricted mobility and so impede the migration of grain boundaries. A parameter 0 L = 0 D m taking into account the effect of triple junctions was varied in the range from 0.003 to 270 (m is the ratio of the triple junction mobility to that of grain boundary and 0 D the initial grain diameter). It was shown that at 0 L <0.4–0.5, i.e. at a small 0 D and small m, the growth kinetics becomes linear. It is supposed that the effect of triple junctions on grain growth can be observed in nanocrystalline materials.

Some Features of the Triple Junction Motion in Aluminium

The migration of the systems of tilt grain boundaries with a triple junction (<100>, <110> and <111>) in high-purity aluminium are presented. The experimental results demonstrate that the motion of grain boundary systems with triple junctions in Al at low temperature can be controlled by slowly moving triple junctions. In the high temperature range the triple junctions less affected the motion of the systems and the activation enthalpy was smaller than that at low temperature. The experiments revealed a drastic difference between activation enthalpy of grain boundary and triple junction motion at different temperatures. The compensation effect (linear dependence of migration activation enthalpy on preexponential mobility factor) at the migration of the systems with triple junction was observed. The compensation temperature was revealed to be close to the temperature for the triple junction mobility.