Eutectic growth behavior with regular arrangement in the faceted Al2O3/Er3Al5O12 irregular eutectic system at low growth rate

摘要

Eutectic growth with regular arrangement (RA) is generally formed in directionally solidified alumina base eutectic in situ composites under high growth rates. In this work, the eutectic growth with RA structure is also observed at low growth rate in Al2O3/Er3Al5O12 composite. The RA structure is formed near primary Al2O3 dendrite in Al2O3/Er3Al5O12 hypoeutectic. Eutectic instabilities especially the single-phase instability lead to the primary Al2O3 phase/dendrite precipitation, and Er3Al5O12 phase nucleated on the Al2O3 substrate is considered as a probable reason of RA structure formation. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.