The distribution of second phase particles in the microstructure of composite ceramics affects the mechanical properties, and the intragranular structures often result in better properties compared to the intergranular structures. However, it is difficult to obtain composite ceramics with intragranular structure by conventional route. To produce composite ceramics with an intragranular structure in a simpler route. In this work, starting powders with different phase compositions were obtained by the co-precipitation method, and zirconia toughened alumina (ZTA) composite ceramics were prepared with these starting powders by spark plasma sintering (SPS). The results show that it is easier to fabricate ZTA composite ceramics with an intragranular structure by using composite powders containing amorphous or transition phase Al₂O₃ as starting materials. The phase composition of the powder prepared by the co-precipitation method after calcination at 1100 °C is θ-Al₂O₃ and t-ZrO₂, and the average grain size after sintering at 1500 °C is 1.04 ± 0.28 µm, and the maximum Vickers hardness and fracture toughness of the specimens reach 19.37 ± 0.43 GPa and 6.18 ± 0.06 MPa·m^1/2, respectively. The ZrO₂ particles were the core of crystallization and grow together with the Al₂O₃ matrix, forming the intragranular structure of ZTA ceramics. This work may provide a new idea for preparing composite ceramics with intragranular structure.

The addition of tungsten can improve the high-temperature oxidation resistance of titanium alloys. However, as its applications continue to expand, new demands are being placed on its room temperature strength. Here, we provide a dense titanium alloy with high strength by introducing proper W powders into the Ti6Al4V powders under direct energy deposition. The effect of tungsten addition on the microstructure and tensile properties of the Ti6Al4V alloy was investigated. Compared to pure Ti6Al4V, the titanium alloy with tungsten addition exhibited refined α′ martensite and β grains, which is attributable to the effect of tungsten on the structural subcooling of titanium and on the formation temperature of the α′ martensite. Owing to the synergistic strengthening effects of grain refinement and solid solution strengthening, the W-containing alloy shows a high tensile strength of 1333 MPa and yield strength of 1219 MPa, which are significantly higher than Ti6Al4V alloy’s tensile strength of 940 MPa and yield strength of 860 MPa. This approach provides a pathway for design and preparation of high-strength titanium alloys by additive manufacturing.

The reliable mechanical properties of ceramizable silicone rubber composites during pyrolysis are necessary for their application in the fire-resistant fields. The effects of liquid-phase amount on the mechanical properties of silicone rubber composites are investigated. The results show a positive correlation between the liquid-phase amount and the flexural strength of the residual products pyrolysis below 800 °C. The nano-γ-Al₂O₃ in the fillers reacts with liquid B₂O₃ to form aluminum borate above 800 °C, which consumes the liquid phase and strengthens the residual products to a certain extent. Increasing the B₂O₃ addition and introducing nano-γ-Al₂O₃ can control the liquid-phase amount in the range of 15% to 30%, which makes the composites have better residual strength and support performance. The residual strength of composites pyrolysis at 500 °C to 1000 °C is higher than 2.50 MPa, and the maximum is up to 18.7 MPa at 1000 °C.