The process of grain growth in 2-dimensional systems was analyzed with respect to the controlling kinetics. These ranged from purely boundary kinetics, where grain growth in a polycrystal was determined by the Von Neumann¯Mullins relationship, to purely triple-junction kinetics, where grain growth was governed by the mobility of triple junctions. It was shown that in the intermediate case, where the driving force for grain-boundary motion and the characteristic mobility were grain-boundary curvature and grain-boundary mobility, respectively, a limited mobility of triple-junctions essentially governed grain-boundary motion. The Von Neumann¯Mullins relationship no longer held, and this was more clear the smaller the triple-junction mobility. In the case where grain growth was determined by the mobility of grain-boundary triple-junctions (triple-junction kinetics), all grains were transformed into polygons during grain growth. The latter would cease if all grains assumed the shape of regular polygons, and not only hexagons as in the Von Neumann¯Mullins case. The only exceptions were triangles. These collapsed without transforming into a polygon. The relationship for the rate-of-change of grain area under triple-junction kinetics was obtained, and considered with regard to microstructural evolution.

Triple Junction Drag and Grain Growth in 2D Polycrystals. G.Gottstein, L.S.Shvindlerman: Acta Materialia, 2002, 50[4], 703-13