Effects of preparation process on microstructure and properties of porous Ti6Al4V

The forced sweat cooling of porous media is an effective way to solve the problem of thermal protection of the leading edge of hypersonic vehicles. The pore structure and performance of porous media have a significant impact on its cooling effect and reliability. Therefore，it is very important to prepare porous materials that meet the requirements of forced sweat cooling. Herein，Ti6Al4V pre-alloyed powders were used as raw materials，and porous Ti6Al4V samples with different open porosity were prepared by compression molding combined with high-temperature sintering. The effect of the sintering temperature and holding time on the microstructures，phase compositions and mechanical properties of the samples were investigated. The results show that increasing the sintering temperature and prolonging the holding time will reduce the open porosity of the material. When the open porosity is high，the pores in the material are connected and the seepage rate is high，while the sample strength is low. When the open porosity is low，large pores in the sample are reduced and the seepage rate decreases，but the strength becomes higher. The porous Ti6Al4V sample with an open porosity of 21.8% shows the best comprehensive performance. When the porous Ti6Al4V sample is used as active thermal protection material，it can withstand flame ablation with an average heat flux of 2.5 MW/m2.