As a key branch of lightweight structural materials, die-cast aluminum-based composites demonstrate significant potential for application in the automotive, aerospace, and other fields, leveraging the low density of the aluminum matrix and the high strength of the reinforcement phase. The aluminum matrix itself possesses excellent thermal and electrical conductivity and processability. The introduction of reinforcement phases such as ceramic particles, fibers, or whiskers through the die-casting process significantly enhances the material’s mechanical properties, particularly in terms of high-temperature strength, wear resistance, and fatigue resistance. For example, in the manufacture of automotive engine cylinder blocks, the use of die-cast aluminum-based composites reinforced with silicon carbide particles not only reduces weight by over 30%, but also withstands higher operating temperatures, extending engine life.
From the perspective of material design, the performance control of die-cast aluminum-based composites is a systematic project. The type, size, volume fraction, and distribution state of the reinforcing phase will directly affect the comprehensive performance of the composite material. Currently, commonly used reinforcing phases include aluminum oxide, silicon carbide, titanium boride, etc. Among them, silicon carbide particles are widely used due to their good interfacial bonding with the aluminum matrix and moderate cost. Studies have shown that when the volume fraction of silicon carbide particles is controlled between 15% and 25%, the tensile strength of the composite material can reach more than 400MPa, which is much higher than the 250MPa of traditional die-cast aluminum alloys. At the same time, by optimizing the particle surface treatment process, such as using silane coupling agent modification, interface defects can be effectively reduced and the toughness of the material can be improved.
The die-casting process is crucial to the molding quality of aluminum-based composites. Compared with traditional aluminum alloy die-casting, the melt fluidity of aluminum-based composites is poor, and the reinforcing phase is prone to agglomeration, which places higher demands on the pressure parameters, mold design, and pouring system of the die-casting equipment. Modern die-casting technology uses a high-vacuum die-casting process to control the gas content in the melt to below 0.1mL/100g, significantly reducing the porosity of the casting. The application of computer simulation technology can accurately predict the filling process of the melt in the mold, avoiding local stress concentration caused by uneven distribution of the reinforcing phase. In addition, post-die-casting heat treatment processes, such as T6 treatment (solid solution + artificial aging), can further eliminate internal stress and optimize the mechanical properties of the material.
Die-cast aluminum-based composites are gradually replacing traditional metal materials in expanding their application scenarios. In the new energy vehicle sector, motor housings made of aluminum-based composites not only meet lightweighting requirements but also enhance heat dissipation efficiency and extend motor life through the high thermal conductivity of the reinforced phase. In rail transit, composite brake components offer wear resistance 3-5 times greater than traditional cast iron parts, significantly reducing maintenance costs. Industry data indicates that the global die-cast aluminum-based composite market will exceed US$8 billion in 2024, with an annual growth rate exceeding 12%.
Despite the significant advantages of die-cast aluminum-based composites, their development still faces several challenges. Uniform dispersion of the reinforcement phase requires high-precision mixing equipment, resulting in high production costs. Composite materials also exhibit poor machinability, with tool wear rates 5-8 times that of aluminum alloys, increasing subsequent processing costs. In the future, with the maturity of nano-reinforcement technology and the development of new die-casting equipment, these issues are expected to be resolved. Furthermore, breakthroughs in recycling technologies will further promote the sustainable development of aluminum-based composites, enabling them to play a greater role in green manufacturing.
