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.