Development of twinned dendrites in aluminum alloys

Feathery grains are similar to kinds of columnar grains and equixed grains in casting structure, which are very important in the field of solidification theory and industry application. Recent researches have revealed that twinned dendrites are the microstructural characteristic of feathery grains. In this paper, we have reviewed the research activities of twinned dendrites, including dendrite tip morphologies, propagation mechanism, growth competition with normal dendrite, and mechanical properties of feathery grains. The factors required for the formation and growth of twin dendrite are discussed. Unsolved problems in twinned dendrites are proposed.