The microstructure and composition of equilibrium phases formed in hypoeutectic Te-In alloy during solidification

As a key tellurium atoms evaporation source for ultraviolet detection photocathode, the hypoeutectic Te75In25 alloy was prepared by employing a slow solidification speed of about 10− 2 K/s. The microstructure and chemical composition of the equilibrium phases formed in the as-prepared alloy were studied in this research work. The experimental results show that the as-prepared Te-In alloy was constituted by primary In2Te5 phase and eutectic In2Te5/Te phases. The eutectic In2Te5/Te phases are distributed in the grain boundaries of primary In2Te5 phase. With the slow solidification speed, a pure eutectic Te phase without any excessive indium solute was obtained, where Te content of eutectic Te phase is 100 mass%. Moreover, it can be considered that the stress between the In2Te5 and Te phases plays an important role in reducing the tellurium vapor pressure in Te75In25 alloy.