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The microstmctural characteristics,elemental distribution law and microscopic formation mechanism of the bing products of TA15 titanium alloy were investigated by friction oxygen concentration method,associated with in situ observation,X-ray diffraction (XRD),scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) analyses,providing the thoughts to improve fireproof property.The results show that,when the friction contact pressure (Pfric) is 0.20 MPa and oxygen concentration of premixed air flow (co) is 60 vol％,TA15 titanium alloy produces violent sparks and presents dazzling white light during combustion.The generated products after bing are mainly TiO2 and small amount of Al2O3 oxides.Four distinct zones form from the combustion surface to the alloy matrix,and they are in the sequence of combustion zone,fusion zone,heat-affected zone and transition zone.Further,combustion zone is composed of TiO2 and A12O3 compounds,containing obvious cracks.In the fusion zone,discontinuous oxygenrich Al-based solid solution forms,and the elemental distribution has strong volatility.In the heat-affected zone,there are abundant of Ti-based solid solution and small amount of A1-and Mo-based solid solution.Transition zone is made of lamellar structure.Two technical approaches are given to prevent oxygen diffusion inside the reaction zone and reaction-affected zone.On the one hand,the content of A1 is designed as the upper limit of alloy composition;on the other hand,fireproof coatings are deposited on the surface of the alloy.