Nanotopography and grain-boundary migration in the vicinity of triple junctions

The grain-boundary topography near the triple junction (TJ) and its evolution at early stages of recrystallization have been studied by the method of field ion microscopy (FIM). The annealing of tungsten leads to the formation of rather large-scale facets and a decrease in atomic roughness. However, in the vicinity of TJ, an increased (up to 1 x 109 m-1) nanofacet density is observed. In deformed tungsten and distribution of TJ in the angles between the grain boundaries shows three peaks at about π/2, 2π/3 and π. The annealing brings about both the decrease in angular dispersion and the peak rise in the region of 2π/3. The stress-induced TJ migration was revealed when annealing tungsten tricrystals in the 2--3 x 1010 V/m electric field. A possible mechanism of grain-boundary nanotopography evolution has been analyzed