Simulation of grain growth in thin films with columnar microstructure

Abstract

Grain growth in films on substrates was simulated under the suppositions that (1) all the grain boundaries have identical energy and mobility, (2) all the grains are columnar and differ in their diameter only, and (3) the growth process is inhibited by a constant drag force depending on the film thickness. The character of grain growth depends on the ratio of the most probable grain diameter in the initial microstructure to the film thickness. In the case when the ratio corresponds to that observed experimentally, the growth process evolves as abnormal grain growth (AG). It has been demonstrated for the first time that the AG process can develop in the absence of an additional driving force. The cessation of AG, when the fine-grained matrix is still present, was shown to result from the exhaustion of relatively small grains that could be consumed. The additional driving force resulting from a decreased surface energy of some grains leads to an increase of the volume fraction of abnormally large grains and to texture amplification. Texture development during grain growth can also take place in the absence of any additional driving force. Intensification of the AG results in texture enhancement.