Research Status and Development of Aluminium Matrix Composite: State of the Art

Aluminum matrix composite is one of the most attractive metal matrix composites. It is a kind of material with strong vitality emerging in response to the needs of modern scientific development. Compared with traditional materials, aluminum matrix composites have the advantages of low density, good electric conductivity and heat conductivity, good wear resistance and oxidation resistance, high specific strength and stiffness, high temperature resistance, good heat treatment performance and flexible preparation process, which make them widely used in the fields of aviation, aerospace, and automobile. In this paper, the factors affecting the properties of aluminum matrix composites, the strengthening mechanism, classification and preparation methods of aluminum matrix composites are summarized. The research status, development direction and application prospect of aluminum matrix composites are briefly introduced.

With the advancement of semiconductor technology, chip cooling has become a major obstacle to enhancing the capabilities of power electronic systems. Traditional electronic packaging materials are no longer able to meet the heat dissipation requirements of high-performance chips. High thermal conductivity (TC), low coefficient of thermal expansion (CTE), good mechanical properties, and a rich foundation in microfabrication techniques are the fundamental requirements for the next generation of electronic packaging materials. Currently, metal matrix composites (MMCs) composed of high TC matrix metals and reinforcing phase materials have become the mainstream direction for the development and application of high-performance packaging materials. Silicon carbide (SiC) is the optimal choice for the reinforcing phase due to its high TC, low CTE, and high hardness. This paper reviews the research status of SiC-reinforced aluminum (Al) and copper (Cu) electronic packaging materials, along with the factors influencing their thermo-mechanical properties and improvement measures. Finally, the current research status and limitations of conventional manufacturing methods for SiC-reinforced MMCs are summarized, and an outlook on the future development trends of electronic packaging materials is provided.

One of the enabling technologies required for commercialization of high efficiency solid oxide fuel cell (SOFC) stacks is the development of low cost ceramic refractories capable of withstanding the harsh environment during start-up and steady state operation. Although low density, high purity fibrous alumina materials have been used for more than two decades in manufacturing of SOFC stack components, their low mechanical strength and high cost have precluded their use in the next generation pre-commercial generator modules. A current trend in SOFC stack design is to use high strength, low purity mullite bonded, cast ceramics which can be produced in large volume at a relatively low cost. Sufficient strength is required to provide structural support of the stack and its upper internals in addition to withstanding the severe thermal gradients in both steady state and transient conditions. To reduce costs while achieving suitable mechanical strength, thermal shock, and creep resistance, certain levels of silica and other impurities are present in the refractory ceramic. Silica, however, has been established to poison SOFC anodes thus degrading cell performance and stack life. Therefore, silica transport within the stack has become a dominant issue in SOFC generator design. As a result, an important design requirement for the stack ceramic materials is to develop a fundamental understanding of the silicon species transport process based on refractory composition and gas atmosphere in effort to minimize silicon species volatilization through the porous material. The vaporization behavior of the Al-Si-O system has been investigated in numerous studies and verified experimentally. It is well known that when aluminum silicate components are exposed to a reducing atmosphere, the partial pressure of oxygen is low, therefore this causes formation of volatile SiO(g). This SiO(g) gaseous phase is transported by the fuel stream to the anode/electrolyte interface and electrochemically oxidizes back into SiO2 over the triple phase boundaries (TPB) by the oxygen transported via the fuel cell. This re-deposition process of SiO2, known also as Si poisoning, blocks the reaction of fuel oxidation as it takes over the reactive sites, leading to noticeable degradation in cell performance. In this paper, the status of research on formation of volatile silicon species in aluminosilicate SOFC insulation materials is examined. The formation of volatile SiO(g), SiO(OH)(g), and SiO(OH)2(g) are indicated to facilitate silicon transport in anode fuel streams. Silica deposition is shown to degrade fuel cell anode performance utilizing a novel SOFC silicon poisoning test setup, and silica deposition is only observed on YSZ in the electrochemically active regions of the cell.

It is difficult for traditional aluminum alloy manufacturing technology to meet the requirements of large-scale and high-precision complex shape structural parts. Wire Arc additive manufacturing technology (WAAM) is an innovative production method that presents the unique advantages of high material utilization, a large degree of design freedom, fast prototyping speed, and low cast. As a result, WAAM is suitable for near-net forming of large-scale complex industrial production and has a wide range of applications in aerospace, automobile manufacturing, and marine engineering fields. In order to serve as a reference for the further development of WAAM technology, this paper provides an overview of the current developments in WAAM both from the digital control system and processing parameters in summary of the recent research progress. This work firstly summarized the principle of simulation layering and path planning and discussed the influence of relative technological parameters, such as current, wire feeding speed, welding speed, shielding gas, and so on. It can be seen that both the welding current and wire feeding speed are directly proportional to the heat input while the travel speed is inversely proportional to the heat input. This process regulation is an important means to improve the quality of deposited parts. This paper then summarized various methods including heat input, alloy composition, and heat treatment. The results showed that in the process of WAAM, it is necessary to control the appropriate heat input to achieve minimum heat accumulation and improve the performance of the deposited parts. To obtain higher mechanical properties (tensile strength has been increased by 28%–45%), aluminum matrix composites by WAAM have proved to be an effective method. The corresponding proper heat treatment can also increase the tensile strength of WAAM Al alloy by 104.3%. In addition, mechanical properties are always assessed to evaluate the quality of deposited parts. The mechanical properties including the tensile strength, yield strength, and hardness of the deposited parts under different processing conditions have been summarized to provide a reference for the quality evaluation of the deposition. Examples of industrial products fabricated by WAAM are also introduced. Finally, the application status of WAAM aluminum alloy is summarized and the corresponding future research direction is prospected.

Diamond/aluminum matrix composite with high thermal conductivity is of great significance to solve the heat dissipation problem of large-scale integrated circuits and high-power components. This paper reviews the current research status of diamond/aluminum matrix composites, and analyzes the effects of the preparation and processing of the composites, the interface bonding between diamond and aluminum matrix, the reinforced diamond and matrix alloy elements on the properties of the composites.

Due to its lightweight, high strength, good machinability, and low cost, aluminum alloy has been widely used in fields such as aerospace, automotive, electronics, and construction. Traditional manufacturing processes for aluminum alloys often suffer from low material utilization, complex procedures, and long manufacturing cycles. Therefore, more and more scholars are turning their attention to the laser powder bed fusion (LPBF) process for aluminum alloys, which has the advantages of high material utilization, good formability for complex structures, and short manufacturing cycles. However, the widespread promotion and application of LPBF aluminum alloys still face challenges. The excellent printable ability, favorable mechanical performance, and low manufacturing cost are the main factors affecting the applicability of the LPBF process for aluminum alloys. This paper reviews the research status of traditional aluminum alloy processing and LPBF aluminum alloy and makes a comparison from various aspects such as microstructures, mechanical properties, application scenarios, and manufacturing costs. At present, the LPBF manufacturing cost for aluminum alloys is 2-120 times higher than that of traditional manufacturing methods, with the discrepancy depending on the complexity of the part. Therefore, it is necessary to promote the further development and application of aluminum alloy 3D printing technology from three aspects: the development of aluminum matrix composite materials reinforced with nanoceramic particles, the development of micro-alloyed aluminum alloy powders specially designed for LPBF, and the development of new technologies and equipment to reduce the manufacturing cost of LPBF aluminum alloy.

Recent progress in laser additive manufacturing of aluminum matrix composites