Microstructure and High-Temperature Mechanical Properties of Ti-6Al-4V/TiAl Matrix Composites using Powder Metallurgy Technology
摘要
The Ti-6Al-4V/TiAl matrix composites were prepared using Ti-6Al-4V and Ti-45Al-5Nb alloy powders by powder metallurgy. The results showed that the structure of the TiAl matrix composites with bimodal structure consisted of fine-grain TiAl matrix, interfaces, and coarse-grain Ti-6Al-4V alloy area. Compared to the TiAl alloy, the TiAl matrix composites exhibited good high-temperature ductility while maintaining high strength. The ductility and strength of TiAl matrix composites are 31 ± 1.5% and 178 ± 3.6 MPa at 900 °C and 1 × 10-4 s-1, respectively, which is 25% higher than that of the TiAl alloy. The improved ductility was attributed to the Ti-6Al-4V alloy particles, which are easily deformable to bear stresses and coordinate the deformation of composite at high temperature. In the meantime, fine grain of TiAl matrix can improve co-deformation ability of the composites. The initiation and propagation of the microcracks are observed in the TiAl matrix and the interfaces boundary during the high-temperature deformation process. In conclusion, the hot workability of the TiAl matrix composites is improved due to the addition of Ti-6Al-4V alloy. Finally, the application prospect of the Ti-6Al-4V/TiAl matrix composites is broadened.