In-situ observation of restoration of tungsten plate via high-temperature confocal laser scanning microscopy

Abstract

The restoration of an yttria dispersion strengthened tungsten plate and the corresponding microstructural evolution are investigated through in situ annealing using high-temperature confocal laser scanning microscopy. The geometrically necessary dislocation density and subgrain/grain evolution at each annealing stage are confirmed using the electron backscatter diffraction technique. The microstructure's evolution is divided into distinct stages of recovery, recrystallization, and grain growth based on their characteristic features. During the recovery process, the fomation of subgrains occurs. The primary mechanism of recrystallization nucleation is dominated by the strain-induced boundary migration mechanism, and the subgrains preexisting at grain boundaries are the main nucleation sites.