Reifbildung

Reifbildung is a term used in physical chemistry and materials science to describe the time-dependent evolution of dispersed microstructures toward larger, more stable units. The process is characterized by changes in size, shape, or degree of ordering of particles, droplets, or crystals within a medium and often leads to a more thermodynamically stable state.

Mechanistically, Reifbildung is driven by diffusion and interfacial energy minimization. In many systems, smaller particles dissolve while material diffuses through the medium and redeposits on larger particles, a phenomenon known as Ostwald ripening. Recrystallization or phase separation can also contribute, particularly in solids undergoing aging or heat treatment.

Contexts include colloidal suspensions, emulsions, and solid precipitates in alloys and ceramics. In precipitation-hardening alloys, aging can trigger Reifbildung as precipitates coarsen, altering hardness and strength. In polymer melts or glasses, crystallization during thermal aging can show similar coarsening behavior.

Consequences vary: overall interfacial area decreases, which may reduce chemical reactivity or diffusion rates; mechanical properties such as yield strength can rise or fall depending on the system; optical or magnetic properties tied to particle size distribution can also change.

Characterization relies on microscopy and scattering methods (electron microscopy, small-angle X-ray or neutron scattering) and time-temperature studies. The timescales range from seconds to days, depending on temperature, concentration, and the mobility of species.

See also Ostwald ripening, coarsening, crystallization, phase separation.