autodifusão

Autodifusão, also known as self-diffusion, is a specific type of diffusion where particles of a substance move due to random thermal motion, without any net external driving force or concentration gradient. In essence, it describes the movement of identical particles within a pure substance. While there is no bulk flow or mass transport from one region to another, individual atoms or molecules are constantly in motion, colliding with their neighbors and changing positions. This movement is driven purely by the kinetic energy of the particles.

The concept of autodifusão is crucial for understanding the fundamental processes occurring within materials at the atomic or molecular level. It plays a significant role in phenomena like annealing in metals, where atoms rearrange themselves to reduce internal stress, and in the relaxation of glasses. The rate of autodifusão is quantified by the self-diffusion coefficient, which is highly dependent on temperature and the material's structure. Higher temperatures generally lead to faster diffusion rates due to increased particle kinetic energy. Autodifusão is distinct from interdiffusion, where different types of particles move across a concentration gradient.