Tensile behavior of the designed SiCf/Ti2AlNb/Ti17 composites

Abstract

SiCf/Ti2AlNb-reinforced Ti17 (SiCf/Ti2AlNb/Ti17) composites were fabricated through hot isostatic pressing. The designed SiCf/Ti2AlNb/Ti17 composites exhibited excellent tensile properties, with tensile strengths of 1657 MPa at room temperature and 1830 MPa at 450 °C. The microstructure, fracture morphology, and longitudinal section of the composites were characterized by X-ray diffraction, scanning electron microscopy, and electron backscatter diffraction techniques. The fracture process of SiCf/Ti2AlNb/Ti17 composites during room-temperature tensile tests was as follows: the SiCf/Ti2AlNb reaction layer first fractured, the crack extended into the Ti2AlNb matrix, the Ti2AlNb matrix crack extended to the adjacent reaction layer and promoted fiber fracture, the crack extended to the Ti2AlNb/Ti17 interface, ultimately the Ti17 capsule fractured. The fracture process of SiCf/Ti2AlNb/Ti17 composites during 450 °C tensile tests was as follows: the SiCf/Ti2AlNb reaction layer first fractured, multiple fiber fractures occurred, and the crack in the reaction layer entered the Ti2AlNb matrix, the crack extended to the Ti2AlNb/Ti17 interface, eventually the Ti17 capsule fractured. The room-temperature tensile fracture was fitted to the LLS model, while the tensile fracture at 450 °C was fitted to the GLS model. The different fracture processes indicated that the SiCf/Ti2AlNb/Ti17 composites were suitable for exploiting fiber strength at 450 °C and therefore exhibited excellent tensile strength.