The high-volume fraction SiC/Al composite is the new type of electronic packaging material, which plays an important role in the field of high-power integrated circuits. In this study, SiC/Al composites with high-volume fraction of SiC particles were prepared by vacuum pressure infiltration. The influence of SiC particle size and NH₄HCO₃ on the pores in the preform was explored, aiming to accurately adjust the volume fraction of SiC to meet the thermal performance requirements in different fields. In addition, the preform was infiltrated with different Al alloys, and the relationship between the porosity and thermal conductivity of SiC/Al was studied. For the SiC preform, the volume fraction of SiC can be adjusted regularly when 12 μm and 100 μm SiC particles are mixed in different proportions, and the volume fraction reaches the maximum when the proportion of coarse particles is about 77%. NH₄HCO₃ is conducive to the connectivity of pores in the preform, and about 40 vol.% of NH₄HCO₃ can effectively increase the porosity of the preform. Thermal conductivity is sensitive to the porosity of composites, especially in the range of 2.5–4.5%. A simple application of the Hasselman–Johnson model and a new thermal conductivity model, λ_d, established in this article, offer a good agreement with the experimental results.

A weldable Al–Mg–Zn–Sc alloy was produced using vacuum induction melting and an argon-protected casting method to achieve high strength and ductility, and the effects of heat treatment on the microstructure evolution and mechanical properties of Al–Mg–Zn–Sc alloys were comparatively investigated. The results reveal that fine equiaxed grains with an average grain size of 40 μm in an as-cast Al–Mg–Zn–Sc alloy change little after heat treatments, bringing about a grain-boundary strengthening of 46.1 MPa. The coarse T-Mg₃₂(Al, Zn)₄₉ phases at grain boundaries are completely dissolved into the matrix through solid-solution treatment, and T-Mg₃₂(Al, Zn)₄₉ with diameters ranging from 10 to 25 nm and Al₃Sc with diameters ranging from 5 to 20 nm gradually precipitate during the artificial aging process. The Mg solid solubility is 4.67% in the as-cast Al–Mg–Zn–Sc alloy, and it increased to 5.33% after solid-solution treatment and dramatically decreased to 4.15% after post-aging treatment. The contributions of solid-solution strengthening to as-cast, post-solid-solution and post-aging Al–Mg–Zn–Sc alloys are 78.2 MPa, 85.4 MPa and 72.3 MPa, respectively. The precipitation strengthening of the post-aging alloy is 49.7 MPa, which is an increase of 21% in comparison to that of both as-cast and post-solid-solution alloys. The alloy achieves an optimal tensile strength of 355.3 MPa, yield strength of 175 MPa and elongation of 22% after undergoing solid-solution treatment.

The internal coupled electromagnetic melt treatment (ICEMT) method is firstly proposed to produce high-quality and large-sized aluminum alloy billets. A three-dimensional model was established to describe the ICEMT process of direct chill casting (DC casting). The effect of ICEMT on the fluid flow patterns and temperature field in the DC casting of ϕ880 mm AA2219 billets is numerically analyzed. Moreover, the mechanisms of the ICEMT process on grain refinement and macrosegregation were discussed. The calculated results indicate that the electromagnetic field appears to be coupled circinate at the cross section of the melt, the fluid flow becomes unstable accompanied by the bias flow, and the temperature profiles are significantly more uniform. An experimental verification was conducted and the results prove that compared with traditional direct chill casting, the microstructures of the AA2219 large-scale billet under the ICEMT process are uniform and fine.

Aiming for hydrogen and oxidation easily produced in the melting process of Al-Mg alloys, three processes, including non-vacuum static melt treatment, non-vacuum rotary-injection purification and vacuum-stirring purification, were used to purify the Al-6Mg alloy melt. The hydrogen content and inclusion content were studied by means of the solid-state hydrogen measurement method, reduced pressure test method, FESEM and EDS. The results show that the purification effect of vacuum-stirring purification is better than that of the non-vacuum static melt treatment and non-vacuum rotary-injection purification. The hydrogen content of the melt decreases from 0.48 mL/100 gAl in the non-vacuum static treatment, to 0.32 mL/100 gAl in the non-vacuum rotary-injection purification process and to 0.10 mL/100 gAl in the vacuum-stirring purification process. The inclusion content of the melt decreases from 2.6% in the non-vacuum static treatment to 0.69% in the non-vacuum rotary-injection purification process, and to 0.39%, in the vacuum-stirring purification process.

Al-Mg alloys were fabricated by hot extrusion process after vacuum + argon-protected casting. The effects of Sc microalloying on microstructure and properties of as-extruded Al-5Mg alloy were studied. The results show that alloy 2 containing Sc is partially recrystallized during hot extrusion, resulting in the structure of alloy 2 consisting of 21.8% equiaxed recrystallized structure and 78.2% fine banding structure. The grain size of alloy 2 is about 5.31 μm, which is 83.3% finer than that of alloy 1 without Sc. The sum of the yield strength increments due to grain boundary strengthening (${\sigma }_{GB}$) in alloy 2 is 103.59 MPa, where low angle grain boundary strengthening (${\sigma }_{LAGB})$ is increased by a factor of 4.5, and high angle grain boundary strengthening $\left({\sigma }_{HAGB}\right)$ is increased by 73.4% compared to that of alloy 1. The addition of 0.2% Sc leads to an increase in the lattice strain and dislocation density of alloy 2, and the dislocation strength (${\sigma }_{dis}$) increases to 41.85 MPa. The alloy 2 with Sc has a higher tensile strength of 380.7 MPa, which is 34.1% higher than that of alloy 1, but alloy 2 has a 46.2% reduction in elongation compared to alloy 1.

Preforms with a volume fraction of 60% were prepared by the compression molding method. SiC/Al composites were prepared by the pressureless infiltration process. Analytical characterization of SiC preforms and SiC/Al composites was obtained using metallurgical microscopy, X-ray diffractometry (XRD), scanning electron microscopy (SEM), etc. The effects of magnesium additives and infiltration atmospheres on the infiltration behavior of aluminum alloy melts and the infiltration characteristics of aluminum alloys in prefabricated bodies were systematically investigated. The results of the study show that: Magnesium as an infiltration aid can remove the oxide film on the surface of the aluminum alloy block, which is conducive to the infiltration of the aluminum alloy melt in the prefabricated body. High purity nitrogen is essential for the success of pressureless infiltration. The reaction of magnesium with the surface of SiC particles during pressureless infiltration improves wettability, which promotes the infiltration of the aluminum alloy melt into the precast.