Thermal shock resistance of hot-pressed SiCw/Si3N4(w=whisker) composites was investigated by thermal shock resistance parameters and water quenching test. The results showed that the thermal shock resistance to fracture initiation and crack-stable repropagation deteriorated with increasing SiCw content in spite of the improvement of fracture toughness, K1C. This could be attributed to the great decrease of strength, σand the considerable increase of Young’s modulus, E, and thermal expansion coefficient, α,resulting from the addition of SiC whiskers. The curves of the residual strength, σ,after water quenching versus thermal shock temperature difference, △T, e.g. σ1-△T, showed good relationships with the calculated thermal stress fracture resistance parameter, R, and thermal stress crack stability parameter, Rst. The crack propagation of SiC whisker reinforced Si3N4 occurred primarily in a quasi-static manner, and it could be mainly attributable to SiC whiskers’ pulling-out and bridging toughening effects.

Nanocrystalline powder with particle size 50 nm and thin film with thickness 2 μm of SrBi2Ta2O9 (SBT) were successfully prepared by the sol–gel method, using strontium acetate semihydrate [Sr(CH3COO)2.1/2H2O] and bismth subnitrate [BiO(NO3)], and tantalum ethoxide [Ta(OCH2CH3)5] as source materials, glacial acetic and ethylene glycol as solvents. The XRD and TEM results indicated that SBT layer-perovskite phase powder obtained has to be single phase, Pt layer had a (100) predominate orientation, and the (115), (200) of SBT thin film formed after being annealed at 800 ℃ for 1 min. The typical hysteresis loop of SBT thin film on Pt/Ti/SiO2/Si was obtained, and the measured Pr and Ps values of the SBT thin film were 5.5 and 8.8 μC/cm2, respectively.

The in situ TiB particle reinforced titanium metal matrix composites were prepared using MA followed by park plasma sintering (SPS) with a heating rate of 50℃/min. The in situ TiB were synthesized by chemical reaction between TiB2 and Ti during the SPS process. The microstructure of the composites sintered at 800, 1000 and 1200℃ were investigated. TiB whiskers are needle-shape and uniformly dispersed in the titanium matrix. The interface between the in situ TiB needles and the titanium matrix is singular and faceted. The composite sintered at 1000℃ has a maximum value of relative density of 99.6%, and good mechanical properties with a flexural strength of 1007 MPa, Young’s modulus of 146 GPa and fracture toughness of 8.64 MPa·m1/2, respectively. The fractographs of all composites exhibit a predominantly brittle cleavage fracture mechanism. The elastic modulus of synthesized TiB was estimated.

An alloy Al-12wt.% Ti-6wt.% Nb was prepared by mechanical alloying (MA) process and its microstructure, mechanical properties and thermal stability were investigated. It was shown that the MA Al-12Ti-6Nb is an Al matrix composite with uniformly distributed intermetallic Al3Ti dispersoids and single phase Nb flakes as well as fine equiaxed Al2O3 and rod-shaped Al4C3 phases. In most of the Al3Ti particles, especially the large ones, island-shaped α-Ti cores are normally retained. After exposure at 550℃ in air for 200h, the Al3Ti dispersoids coarsen slowly and their α-Ti cores disappear, while the single phase Nb remains. Compared with the MA Al-12Ti fabricated in the same way, the MA Al-12Ti-6Nb shows much more excellent mechanical properties and thermal stability, which can be attributed to the more effective reinforcement of Al3Ti dispersoids and Nb flakes due to the alleviation of their thermal expansion mismatch with the Al matrix by the addition of Nb.