korngränser

Korngränser are the interfaces separating adjacent crystalline grains in polycrystalline materials. In metallurgy and materials science, each grain is a region in which the crystal lattice is oriented in a uniform direction. The grain boundary, or Korngrenzer, is where the lattice orientation changes abruptly, creating a defect line in the crystal structure. These boundaries are typically a few atomic layers wide, but the concept can extend to larger microstructural features in some contexts.

The presence and properties of Korngränser profoundly affect a material’s mechanical, electrical, and thermal behaviour. Grain boundaries can impede dislocation motion, thereby strengthening a metal (the Hall‑Petch effect). They also serve as sites for diffusion and segregation of impurities, influencing corrosion resistance and embrittlement. In polycrystalline silicon, for example, Korngränser limit carrier mobility, which is critical for semiconductor performance.

Identification and characterization of Korngränser are carried out through several techniques. Electron backscatter diffraction (EBSD) in scanning electron microscopes provides grain orientation maps and boundary character distributions. High‑resolution transmission electron microscopy (HRTEM) visualises the atomic structure directly, revealing boundary misorientation angles and defect configurations. Atom probe tomography can map the concentration of elements at the boundaries, showing segregation phenomena.

Understanding Korngränser is essential for tailoring material properties. By controlling grain size through thermomechanical processing, engineers can optimize strength, toughness, and conductivity. In nanocrystalline materials, the high density of Korngränser leads to unique mechanical behaviours such as superplasticity. In fuel cells, engineered grain boundary networks improve ionic conductivity. Consequently, research on Korngränser remains a focal point in advanced materials development.