Model Calculations of ContinuousGrain Growth in Textured Materials

Continuous grain growth of a polycrystalline structure proceeds by the simultaneous movement of all grain boundaries driven by the grain boundary energy and controlled by the boundary mobility. In the present model calculations, energy and mobility are allowed to depend on the orientation difference between neighbouring crystals. The growth process then depends on the misorientation distribution function. In a first approximation the orientation correlations are assumed to be random. Then the MODF can be expressed by the texture. A simple growth model leads to a continuity equation depending on crystal orientation g and grain radius r which can be integrated for the steady state case in which the texture and the shape of the grain size distribution curve remain constant. The same solution also serves as an approximation for pseudo-steady state cases with slowly varying texture. More general solutions are obtained by adding several pseudo-steady state solutions. The specific case of two pseudo-steady state components is considered in detail. Thereby the growth kinetics, texture changes and the form of the grain size distribution curves is obtained.