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Co-Cu composite powders with different Cu contents were synthesized via an ultra-rapid solution combustion synthesis (SCS) method and WC-10(Co/Cu) cemented carbides with an ultrafine grain size were prepared by microwave sintering the compacts of powder mixes of WC and the Co-Cu composite powders. The effects of Cu addition on the microstructure and properties of the microwave-sintered WC-Co cemented carbides were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), field emission transmission electron microscopy (FE-TEM) and mechanical properties tests. The results showed that the addition of a small amount of Cu instead of Co in the WC-Co cemented carbides enhances the sintering, restrains the WC grain growth and improves the mechanical properties. The average WC grain size decreases as Cu is added, and the grain size distribution narrows. The Rockwell hardness and fracture toughness of the WC-10(Co/Cu) alloys with a 0.5 wt% Cu addition reach 90.7 HRA and 14.3 MPa m−1/2, respectively. In addition, the transverse rupture strength (TRS) reaches 2544.7 MPa with a 1 wt% Cu content. The present results show that Cu-doped WC-Co cemented carbides have excellent comprehensive performances.

In this paper, high-Si reinforced Al matrix composites (H-Si/Al) with Si mass ratio 50–70% were successfully fabricated from the powder mixture of Si and Al by a novel route called as powder semi-solid squeeze. It is found that no Al–Si lamellar eutectic in the composites. As the Si content increases, fine Si particles in the H-Si/Al are reduced and the coarse Si particles may increase in size, or gather together to form twisted large particles and even form a space network structure. With the Si content ranging from 50% to 70%, The flexural strength varies between 248 and 179 MPa, the mean coefficient of thermal expansion from ambient temperature to 100 °C can be regulated between 11.32 and 7.55 × 10 −6 °C −1 , and the thermal conductivity varies between 140 and 120 W m −1 °C −1 , showing that H-Si/Al prepared by powder semi-solid squeeze have excellent mechanical and thermal properties.

Commercial F500 SiC powder and 6061 Al powder were chosen to fabricate the 50 vol.-% SiCp/6061Al composites via pressureless sintering. Effects of pre-treatment of the SiC powder and sintering temperature on the microstructures and properties of the composites were studied. Densification mechanism and interfacial reaction of the composites were also investigated. The results show that the composites have a high sintering ability and a low interfacial reaction activity. The density, bending strength and thermal conductivity of the composites are all sensitive to the sintering temperature. The composites sintered at 680°C are nearly fully dense and have the following optimal properties: the relative density of 98.5%, the bending strength of 495 MPa, the TC of 153 W/(m K) and the coefficient of thermal expansion of 8.1 × 10−6/°C (50–100°C), which are superior to most of the SiCp/Al composites of the similar composition reported previously.

SiC/Al composites with uniformly distributed SiC particles were fabricated by pressureless infiltration of liquid AlSi7Mg alloy into SiC preforms with different porosity derived from SiC powders. The linear expansion of SiC preforms without any deformation was about 4% due to the oxidation of SiC powders during the sintering process. SiC preforms had no change in both shape and dimensions after infiltration so that near-net-shape composites were achieved. As SiC volume fraction varies from 39% to 62%, the thermal conductivity of SiC/Al composites with bending strength beyond 360 MPa and elastic modulus beyond 140 GPa varies from 146 to 118 W m−1 K−1 at room temperature, and the mean linear coefficient of thermal expansion from room temperature to 373 K varies from 10 × 10−6 to 7.69 × 10−6 K−1, agreeing better with the Turner's model.