Different solidification behaviours of Bi–10wt%Te alloy induced by liquid structural change

Abstract

By means of DC four-probe technique, the temperature dependence of the electrical resistivity (ρ–T) of liquid Bi–10wt%Te alloy has been measured. Two abnormal changes on the ρ–T curve within the temperature ranges of 497–550°C and 639–708°C suggested that two irreversible liquid–liquid structural changes (LLSC) occurred. To explore the effects of the LLSC on the solidification behaviour of the alloy, solidification experiments were carried out. The results show that after experiencing LLSC, there will be enlarged undercooling, much finer microstructures and larger quality of Bi₂Te phase. Moreover, the morphology of solidified Bi₂Te is changed from dendrite to equiaxed.

Keywords:

• Bi–10wt%Te
• liquid–liquid structural change
• solidification
• undercooling

Acknowledgements

This work has been supported by National Natural Science Foundation of China (Grants No. 50371024 and 50571033) and by the Provincial Natural Science Foundation of Anhui (Grants No. 070416234 and 070414178).