High-performance titanium-based composite strengthened with heterogeneous network structure

Abstract

By adjusting the particle size of Ti6Al4V(TC4) powders and the distribution of boron particles, a high-performance heterogeneous network structure titanium matrix composites were fabricated through the spark plasma sintering (SPS) technique. In the present work, TiB whisker (TiBw) are in situ synthesized around the boundaries of the small size TC4 (STC4) particles, and formed into a TiBw network structure. The STC4 particles of the network surround the larger size TC4 (LTC4) particles to form a new heterogeneous network structure similar to the shape of a sunflower. The heterogeneous network structure consisted of coarse grain zones (LTC4) and fine grain zones (TiB/STC4) is formed in the microstructure. In light of tensile results, the tensile strength and ductility of TiB/TC4 composites with heterogeneous network structure are about 987.5 MPa and 11.5 %, respectively, which are 16.6 % and 35.3 % higher than those of TC4 alloy. The improvement of mechanical properties is mainly due to the interface strengthening mechanism of heterogeneous network structure and the hindrance and pinning mechanism of reinforcements to dislocation movement. The improvement of ductility depends on the inhibition of crack propagation by the heterogeneous network structure and the existence of high ductility coarse grain zone.