Abstract
Deformations of grain and grain boundary of polycrystalline Ni-Zn ferrite were studied by microscopic method, which seem to play some important roles on the densification during hot-pressing process as well as diffusion mechanism. Polycrystalline specimen of Ni-Zn ferrite with the size of 10×10×10 mm was compressively deformed at a temperature range from 1250 to 1360°C. Even at a fairly low temperature (1250°C), grain boundary sliding (the quantity was very small though), plastic deformation of grain itself by dislocation movement, developement of cross and wavy slips in a grain, and rotation of a grain in the polycrystal were observed without failure of the polycrystal. And also, with these deformations of grain, grain boundary was slightly corrugated. At higher temperatures, remarkable changes different from those lower temperature deformation modes were characterized by grain boundary migration and corrugation. Especially, grain boundary migrated in the same manner as thermally activated grain growth and the ghost lines distinctly remained in the original place of grain boundary after the boundary migration. These ghost of grain boundary may have important effects on the segregation of chemical constituents of the ferrite in grain boundary region.
