Wenbo Yu

Synthesis, microstructure and mechanical properties of a bio-inspired Ti-intermetallic multi-layered/SiCf-reinforced Ti-matrix hybrid composite

In reference to the crack deflection ability of multi-layered keratin and the fibers reinforcement of the dorsal cortex in the turtle shell carapace, a bio-inspired composite of Ti-intermetallic multi-layered/SiCf-reinforced Ti matrix was successfully fabricated through vacuum hot-pressing sintering using pure titanium foils, pure aluminum foils and continuous SiC ceramic fibers. Our observation reveals that Ti-intermetallic multi-layers were well bonded to each other with the formation of in situ Ti3Al, TiAl, TiAl2 and TiAl3 phases between Ti layers. At the same time, SiC fibers were firmly bonded to the Ti matrix through a circular joining of TiC achieved by the reaction between the deposited coating of C and the Ti matrix. Due to the strengthen effect of continuous-SiCf-reinforced Ti-matrix part, the tensile and the flexural strengths of the hybrid composite along the longitudinal direction of the fibers were about 636xa0±xa040 and 889xa0±xa050xa0MPa (Ti-intermetallic multi-layered part stressed in tension) or 984xa0±xa050xa0MPa (continuous-SiCf-reinforced Ti-matrix part stressed in tension), respectively. These values were much higher than those obtained from Ti-intermetallic multi-layered composite, corresponding to 404xa0±xa030 and 462xa0±xa030xa0MPa. In addition, the Ti-intermetallic multi-layered composite showed higher fracture toughness value (34.7xa0±xa01.2xa0MPaxa0m1/2) than that of continuous-SiCf-reinforced Ti-matrix composite (24.8xa0±xa00.1xa0MPaxa0m1/2). In drop hammer impact test, the hybrid composite exhibited better crack resistance and higher absorb energy when the U notch was in Ti-intermetallic multi-layered side, other than U notch in continuous-SiCf-reinforced Ti-matrix part. Herein, it is deduced that the hybrid composite combines the crack deflection ability of Ti-intermetallic multi-layered structure and strengthen effect of continuous SiC fibers.