Design and Development of Metal Matrix Composites

1. Introduction

Metal Matrix Composites (MMCs) constitute a class of advanced materials distinguished by their exceptional mechanical, thermal, and tribological properties, offering significant advantages over conventional metals and alloys. These materials consist of a metal or alloy matrix reinforced with ceramic particles, fibers, or whiskers, leading to a unique combination of high strength, stiffness, wear resistance, and, in some cases, enhanced thermal or electrical conductivity. As a result, MMCs are increasingly employed in high-performance structural and functional applications in the aerospace, automotive, defense, and electronics industries [1,2,3,4].

The development and optimization of MMCs constitute a highly interdisciplinary endeavor, bridging core principles of metallurgy, materials science, and mechanical engineering with emerging trends in advanced manufacturing technologies, including additive manufacturing (3D printing), powder metallurgy, spark plasma sintering, and friction-based processing methods, which have opened new avenues for tailoring microstructures and achieving superior composite performance [1,3,4].

This Special Issue was conceived as a comprehensive platform consolidating cutting-edge research and technological developments that address both the scientific foundations and practical challenges associated with MMCs. The contributions cover a broad spectrum of topics, such as innovative manufacturing techniques, interfacial engineering, microstructural design, mechanical behavior modeling, and the development of hybrid or functionally graded composites.

The aim of this Special Issue is to highlight recent advances that deepen our understanding of MMCs’ behavior under various service conditions and foster their integration into industrial applications. A further aim is to present experimental investigations, computational approaches, and case studies that demonstrate MMCs’ potential in solving complex engineering problems. The selected contributions reflect the growing maturity and strategic importance of MMCs as key enablers in the design of next-generation materials and systems.

2. An Overview of the Published Articles

This Special Issue comprises ten original contributions that collectively illustrate the breadth of current research on Metal Matrix Composites (MMCs), spanning advanced processing techniques, multiscale modeling, and performance evaluation under extreme conditions.

Johanes et al. (contribution 1) present an experimental investigation of Mg/SiO₂ nanocomposites subjected to various cryogenic temperatures, revealing how cryo-treatment alters grain structure, dislocation density, and phase distribution, ultimately impacting thermal conductivity and compressive strength. Interestingly, they show that ultra-low temperatures do not always lead to superior performance, challenging conventional assumptions and offering new pathways for optimizing thermal designs.

Monteiro and Simões (contribution 2) examined the fabrication and behavior of hybrid nanocomposites based on Al6061 alloy reinforced with ceramic nanoparticles. Their work details the dispersion methods, sintering parameters, and resulting improvements in hardness, tensile strength, and corrosion resistance, demonstrating how hybridization strategies can be used to fine-tune material properties, especially for lightweight applications where the strength-to-weight ratio is critical.

Kunčická et al.’s work (contribution 3) focuses on high-shear deformation applied to powder-based copper composites. Using high-resolution microscopy and mechanical testing, they show that such processing leads to significant grain refinement, texture development, and enhanced mechanical strength. Electrical conductivity is also preserved at high levels, indicating the technique’s suitability for high-performance electronic components.

Walunj et al. (contribution 4) investigated titanium substrates coated with different ceramic materials—including TiN, TiC, TiCN, TaN, and NbN—using spark plasma sintering. The coatings were evaluated in terms of microhardness, frictional behavior, and resistance to wear. The authors concluded that specific ceramic phases significantly improve surface durability and biocompatibility, providing strong support for applications in biomedical implants and aerospace components.

Wang and Zhang (contribution 5) present the synthesis of MoSi₂–SiC composites through an innovative two-step spark plasma sintering (SPS) process. They emphasize how a controlled reaction between Mo and Si powders, in the presence of in situ-formed carbon, enables a uniform dispersion of SiC particles. The resulting composites exhibit high-temperature stability, low thermal expansion, and increased fracture toughness, making them ideal for use in turbines and thermal protection systems.

Wan et al. (contribution 6) delved into La₂O₃-reinforced A356 aluminum alloy composites. Through systematic variation of the reinforcement content, they assessed tensile strength, elongation, and electrochemical corrosion resistance. Advanced characterization techniques, such as SEM and XRD, revealed the role of La₂O₃ in refining grain boundaries and forming protective oxide films, making these composites promising for marine and automotive environments.

Liu et al. (contribution 7) explored eutectic high-entropy alloys (EHEAs) based on AlCrFeNi with silicon doping. Their work demonstrates that Si incorporation promotes the formation of dual-phase microstructures—consisting of a BCC matrix and intermetallic phases—leading to a balanced combination of high yield strength and ductility. The research bridges the gap between traditional MMCs and emerging HEA design philosophies.

Akarou et al. (contribution 8) utilized atomistic simulations to model Cu-Mo nanocomposites and examine interfacial behavior at the atomic scale. By testing multiple interatomic potentials, they identified the most accurate models for representing Cu-Mo bonding. Their results highlight how interface characteristics—such as misfit dislocation arrays and shear response—affect mechanical performance, offering insights crucial for the design of multilayered nanostructures.

Kunčická and Kocich (contribution 9) contribute a second study focused on Cu-La₂O₃ composites processed via Equal Channel Angular Pressing (ECAP). They combined experimental deformation analysis with finite element modeling to predict strain distribution and grain refinement. The addition of La₂O₃ improved strength and thermal stability, supporting the use of ECAP as a viable route for producing ultrafine-grained functional composites.

Xi et al. (contribution 10) provide a theoretical study on the Sc₃AlC MAX phase under high-pressure conditions using first-principles calculations. Their analysis includes the evolution of lattice parameters, elastic anisotropy, electronic band structure, and dislocation core energies. Their work uncovers the pressure-dependent behavior of the material, revealing its potential for extreme environments where both structural resilience and electronic functionality are required.

3. Conclusions

This Special Issue on the Design and Development of Metal Matrix Composites offers a thorough and multifaceted perspective on the latest advancements and future directions in the rapidly evolving field of MMCs. By offering a diverse array of high-quality contributions, this issue not only enhances our understanding of the underlying physical mechanisms, interfacial phenomena, and microstructural evolution inherent to these composites but also showcases novel fabrication strategies and practical applications useful for a wide range of industrial sectors.

The collected works reinforce the strategic relevance of MMCs in addressing the growing demands for lightweight, high-performance, and durable materials in critical areas such as the aerospace, automotive, biomedical engineering, defense, and renewable energy industries. Furthermore, they highlight the transformative potential of integrating computational modeling, advanced experimental techniques, machine learning, and design optimization into the development pipeline of MMCs—paving the way for smarter, more efficient, and sustainable material systems.

Importantly, this Special Issue underscores the value of interdisciplinary collaboration, wherein materials scientists, mechanical engineers, manufacturing specialists, and computational researchers converge to tackle complex challenges in MMC research and applications. The synergies between theory, processing, characterization, and performance evaluation contribute to a more holistic approach to composite materials design.

We hope that the insights and innovations presented herein will serve not only as a state-of-the-art reference for current practitioners but also a catalyst for future investigations. By encouraging dialogue and collaboration across disciplines, we hope that this Special Issue supports the continued evolution of MMCs toward increasingly sophisticated, customized, and impactful solutions for next-generation technologies.