Abstract:The combustion behavior of Ti-Al-Mo-Zr-Sn-W alloy (TC25G) was studied in a high-temperature and high-speed air flow environment using the laser ignition method combined with ultra-high temperature infrared thermometer, scanning electron microscope, X-ray diffractometer, and transmission electron microscope. The burn-resistant performance of TC25G and TC11 alloys was compared. Meanwhile, the microstructural characteristics, crystal structure, and formation mechanism of the combustion products of TC25G alloy were analyzed in detail. The results show that the high-temperature and high-speed air flow promotes combustion within the air flow temperature range of 200–400 °C and the air flow velocity range of 0–100 m/s. The combustion path advances along the direction of the air flow. The combustion of TC25G alloy mainly relies on the diffusion of the oxygen and the expansion of the combustion area caused by the movement of the melt. Based on the microstructure and composition of combustion product, it can be divided into the combustion zone, the melting zone, and the heat affected zone. During combustion, the formation of microstructures is closely correlated with the behavior of alloying elements and their selective combination with O. The major oxidation products of Ti are TiO and TiO2. The oxides formed by Mo and W hinder the movement of the melt during the combustion. Al and Zr tend to undergo internal oxidation. Al2O3 precipitates on the surface of ZrO2, forming a protective oxide layer that inhibits the inward diffusion of O. Moreover, the element enrichment at the interface between the melting zone and the heat affected zone increases the melting point on the solid side, hindering the migration of the solid-liquid interface.