The in situ synthesized TiB reinforced titanium matrix composites have been prepared by spark plasma sintering at 800–1200 ℃ under 20 MPa for 5 min. The effects of sintering temperature and reinforcement volume fraction on flexural strength, Young’s modulus and fracture toughness of the composites are investigated. The titanium matrix consists of α-Ti and β-Ti phases, and the volume fraction of β-Ti increases with increasing sintering temperatures. The in situ synthesized TiB reinforcements are distributed randomly and uniformly in matrix. The transverse section of TiB has a hexagonal shape aligned along [010] direction, and the crystallographic planes of the TiB needles are always of the type (100); (101) and (101). The 10 vol% TiB reinforced composite sintered at 1000 ℃ exhibits excellent mechanical properties. The flexural strength, Young’s modulus and fracture toughness of this composite are 1560 MPa, 137 GPa and 8.64 MPa·1/2, respectively.

Chitosan/magnetite nanocomposite was synthesized induced by magnetic field via in situ hybridization in ambient condition. Results of XRD patterns and TEM micrographs indicated that magnetite particles with 10–20nm were dispersed in chitosan homogeneously. An interesting result is that magnetite nanoparticles were assembled to form chain-like structures under the influence of the external magnetic field, which mimics the magnetite chains inside of magnetotatic bacteria. The saturated magnetization (Ms) of nano-magnetite in chitosan was 50.54 emu/g, which is as high as 54% of bulk magnetite. The remanence (Mr) and coercivity (Hc) were 4 emu/g and14.8 Oe, respectively, which indicated that magnetite nanoparticles were superparamagnetic. The key of route is that a preprecipitated chitosan hydrogel membrane, used as chemical reactor, which controlled the precipitation of chitosan precipitation and in situ transformation of magnetite from the precursor simultaneously in the magnetic field environment.

In situ TiB whiskers have a hexagonal shape in the transverse section and grow along the [010]TiB direction. The crystallographic planes of the TiB whiskers in the transverse section are always (100), (101) and (101). The stacking faults in TiB are typically with a stacking fault plane of (100)TiB. The locations of boron atoms and the lattice mismatch energy between TiB and Ti matrix play key roles in the formation of stacking faults.

The ambient and elevated temperature mechanical properties of two kinds of hot-pressed fused silica matrix composites, SiO2+5vol.% Si3N4 and SiO2+5 vol.% Si3N4+ 10 vol.% Cf, were investigated. Si3N4 additions greatly enhanced the ambient strength and fracture toughness, while, further incorporation of chopped carbon fibers only but sharply increased the fracture toughness value from 1.22 to 2.4 MPa m1/2. The strength of the two composites synchronously exhibited anomalous gains at certain elevated temperature range especially from 1000 to 1200 ℃, and reached their maximum values at 1000℃, 168.9 and 130.6 MPa, which were 77.0 and 77.4% higher than their ambient strength, respectively. The two composites exhibited catastrophic fracture even at 1000 ℃, but manifested prominent plastic deformation at 1200 ℃ and usually no fracture occurred during the strength test. Vickers’ indentation crack propagation behavior, combined with fractographs studies, suggested that toughening from carbon fiber was attributed primarily to the fiber bridging, pull-out and crack deflection.

Silicon nitride (Si3N4) ceramics incorporated various amount of titanium diboride (TiB2) were fabricated by hot pressing at 1800℃ for 1 h. The influence of TiB2 on the microstructure and mechanical properties of Si3N4 ceramic was investigated. When a small amount of TiB2 (2vol.%) was added, the mechanical properties of Si3N4 were improved significantly, whereas they began to degrade when more TiB2 (＞4vol.%) was introduced. The reaction between TiB2 and Si3N4 matrix is responsible for the variation in mechanical properties of the TiB2/Si3N4 composites.