Körnergrenzendiffusion

Körnergrenzendiffusion is a phenomenon observed in materials science, specifically concerning the movement of atoms or molecules across the boundaries of individual grains within a polycrystalline structure. Grains are crystalline regions with a defined orientation, and their boundaries represent interfaces where these orientations change. These grain boundaries are often less ordered and possess higher energy compared to the bulk of the grain, making them more susceptible to diffusion.

This type of diffusion is generally faster than bulk diffusion, which occurs within the interior of the grains. This is because the disordered atomic structure at grain boundaries provides more pathways and lower activation energy for atomic migration. Consequently, mass transport along grain boundaries can significantly influence the overall diffusion rate in a material, particularly at lower temperatures where bulk diffusion is slow.

The rate of Körnergrenzendiffusion is influenced by several factors, including the temperature, the type of diffusing species, and the nature of the grain boundary itself (e.g., its misorientation and structure). Understanding Körnergrenzendiffusion is crucial for predicting and controlling material properties such as sintering, creep, and the formation of precipitates. It plays a significant role in processes like carburization, decarburization, and the diffusion of dopants in semiconductors.