On the correlation between solidified microstructures and liquid structural states in Bi-40 wt%Te alloy

The compound-forming alloy Bi-40wt%Te was selected to explore effects of the temperature-induced liquid-liquid structure transition (TI-LLST) on solidification. The resistivity-temperature pattern of the molten alloy suggested that an irreversible TI-LLST occurred from 694.6 to 723.2 degrees C as temperature elevated. When solidified from the melt undergoing the TI-LLST, the solidification undercooling of the primary phase Bi2Te3 was enlarged and its growth manner was obviously changed, resulting in the spirally curling refined branches, contrary to the orientated thick rod-like crystals solidified from the melt failed to undergo the TI-LLST. Moreover, the volume fraction of the peritectic phase increased from 30.6% to 56.4%, which implied that the phase competition behavior during the peritectic reaction was also changed. (C) 2009 Elsevier B.V. All rights reserved.