Through investigating electric resistivity-temperature curves of Sn-6Bi alloy melt

two kinds of liquid-liquid structure transition（LLST） were irreversible LLST at high temperature stage（890

1

095 ℃） and reversible LLST at low temperature（645 ℃） were observed at different temperature zone.The irreversible LLST is attributed to the transition of metastable Sn SROs and（Bi）n SROs

while the tetrahedral Sn-Sn SROs can be broken or dissolved into smaller ones during heating cycle

and to be rebuilt during subsequent cooling process

which is responsible for the reversible LLST.Based on the observation

the solidification experiments were carried out.With the melt experienced LLST from temperature induction

the solidification undercooling is increased

and solidified time is postponed with the slightly decrease of solidification latent heat

refining evidently solidification microstructure.