The wettability of the metal/SiC system is not always excellent, resulting in the limitation of the widespread use of SiC ceramic. In this paper, three implantation doses of Si ions (5 × 10¹⁵, 1 × 10¹⁶, 5 × 10¹⁶ ions/cm²) were implanted into the 6H-SiC substrate. The wetting of Cu-(2.5, 5, 7.5, 10) Sn alloys on the pristine and Si-SiC were studied by the sessile drop technique, and the interfacial chemical reaction of Cu-Sn/SiC wetting couples was investigated and discussed. The Si ion can markedly enhance the wetting of Cu-Sn on 6H-SiC substrate, and those of the corresponding contact angles (θ) are raised partly, with the Si ion dose increasing due to the weakening interfacial chemical reactions among four Cu-Sn alloys and 6H-SiC ceramics. Moreover, the θ of Cu-Sn on (Si-)SiC substrate is first decreased and then increased from ~62° to ~39°, and ~70° and ~140°, with the Sn concentration increasing from 2.5%, 5% and 7.5% to 10%, which is linked to the reactivity of Cu-Sn alloys and SiC ceramic and the variation of liquid-vapor surface energy. Particularly, only a continuous graphite layer is formed at the interface of the Cu-10Sn/Si-SiC system, resulting in a higher contact angle (>40°).

Composites reinforced by nano-ceramic particles typically result in the formation of clustering and a weak interface. The spatial distribution of particles and the wetting behavior remarkably affect the targeted properties. Here, a surface modification combined spatial control solution was demonstrated to prepare nanocomposites with homogeneous micro-structures. Poly-crystalline nano-MgAl₂O₄ particles that possess a good crystallographic orientation relationship with Al were coated on the surface of ceramic particles, and they were macro- and then microscopically dispersed in the melt by ultrasonic vibration with variable frequency. The reason this is that the acoustic pressure distributed in the Al melt can induce the acoustic streaming and cavitation. A model for calculating equilibrium particle migration velocity was proposed, based on which the distribution of particles could be controlled by adjusting the solidification rate and the size of particle clustering. The experimental results were validated by the prediction of the model. In addition, it was found that the relationship of the maximum radius angle with the contact angle was ${\omega }_0=180°-\mathsf{\theta }$, and ultrasonic vibration could provide enough energy for the later stage entering of particles to overcome the energy barrier.

The composite components with complex-shape and containing different nanoparticle contents and sizes were successfully produced by the short-process thixoforming. Based on the developed constitutive model, numerical simulation of thixoforming for the composites with a high solid fraction was carried out, and the relevant experiments were performed. The influences of temperature and forming rate on strain-stress were analysed. Furthermore, the effects of temperature, moving rate of the die and holding time on the filling behaviour were discussed. Results of numerical simulation revealed that at high temperature and high forming rate, uniformly distributed stress-strain field and reduced maximum forming force could be obtained, which is advantageous for avoiding the non-uniform composition and incomplete filling caused by liquid-phase segregation; they were consistent with experimental results. After T6 heat treatment, the average yield strength and ultimate tensile strength of the parts were significantly improved. Moreover, the fracture mechanism of the part was discussed.