Microstructure, densification and mechanical properties of in situ TiBw/Ti2AlNb composites fabricated by spark plasma sintering

TiB whisker-reinforced Ti2AlNb (TiBw/Ti2AlNb) composites with a network architecture were fabricated by the spark plasma sintering (SPS) technique at the temperature ranging from 950 to 1250 degrees C with the pressure range of 15-50 MPa for 5-30 min and followed by furnace cooling. The effects of SPS parameters and the volume fraction of TiB2 on the microstructure, densification, phase composition and mechanical properties of the sintered composites were studied in detail. The results revealed that the microstructure of TiBw/Ti2AlNb composites was related to the degree of in situ reaction, which was linked to sintering temperature, time, pressure and the volume fraction of TiB2. The TiBw/Ti2-AlNb composite exhibited the highest strength and plasticity at room temperature with the sintering process of 1200 degrees C/15 min/50 MPa/2.5 vol. % TiB2, and its ultimate tensile strength was nearly 240 MPa higher than that of SPS sintered Ti2AlNb-based alloy. However, its high-temperature mechanical properties were lower than those of SPS sintered Ti2AlNb-based alloy, which is due to the fact that the bonding strength between high-strength TiB whiskers and Ti2AlNb matrix was worse during hot deformation, the interface deboned before fracture, and the strengthening effect of TiBw decreased. Compared with the traditional TiBw-titanium alloys system, this work systematically discussed the influence of various parameters on the microstructure and mechanical properties of the composites under TiBw-Ti2AlNb-based alloys system, which can eventually enrich the application of network architecture in the field of powder metallurgy to improve the mechanical properties of materials and provide guidance for the optimization of process parameters.