The dependence of phase selection in peritectic solidification of Bi–Te40 on cooling rates and liquid states

During peritectic reactions of the alloy Bi–Te40 (wt%), the phase selection was studied from the viewpoint of heat treatment. The results unambiguously show that the alloy solidification manner is dissimilar to that demonstrated in present Bi–Te phase diagrams. At the cooling rate from 0.69 °C/Sec to 104°C/Sec or during the isothermal process, Bi4Te5 is confirmed to develop at the first peritectic reaction L + Bi2Te3 → Bi4Te5. The second peritectic reaction L + Bi4Te5 → BiTe may occur only when the cooling rate is slow enough, about 100 °C/s. The peritectic reactions both proceed more incompletely with increasing cooling rate. However, the intermetallic phase Bi6Te7 could not be checked under all the conditions. More significantly, after experiencing liquid–liquid structural change, there will be a large quantity of peritectic phases with refined microstructures.