Enhancing high-temperature mechanical property of TiC/Ti2AlNb composite via core-shell microstructure

This study synthesized and characterized the TiC/Ti2AlNb composites with core-shell microstructure by spark plasma sintering (SPS), and grain refinement was achieved by the in-situ generated primary TiC at the grain boundaries. Meanwhile, the ultimate tensile strength (UTS) of the TAN-2 composite increased from 325.6 MPa to 368.4 MPa at 700 degrees C with the support of TiC precipitates. Cooling phase change process, the rapid diffusion of carbon atoms at the interface results in the secondary TiC originating from the B2 phase. Notably, Ti2AlNb alloy and TAN-X composites exhibited intergranular fracture due to the concentrated precipitation of the O phase at the grain boundary, and the combined action of the O phase and grain boundary defects accelerated the fracture failure of the alloy. After adding carbon, in situ generation of TiC improved the ability of grain to combine, and strengthened the composites.