Crystallography of engulfed and pushed TiB2 particles in aluminium

TiB2 particles were observed at the grain boundaries of an Al casting, suggesting they were pushed during solidification; however, a small proportion were retained within the alpha-A1 grains due to engulfment. Crystallographic analysis of the TiB2 with the surrounding alpha-Al showed that very few particles segregated to the grain boundaries showed any systematic relationship, while 70% of the engulfed particles display one of two orientation relationships, suggesting that the formation of a low-energy crystallographic relationship assists engulfment. (C) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.