Herein, the investigations conducted in the area of aluminum (Al) matrix composites reinforced with carbon nanotubes (CNTs) are presented. The application of CNT reinforcement in Al alloys is driven by its exceptional chemical and mechanical properties. The critical issues in the processing techniques, challenges in the interfacial mechanisms between the Al matrix and CNTs, and strengthening effects due to the presence of reinforcements are reviewed. The mechanical properties of CNT/Al composites are found to be effectively enhanced with an addition of CNTs even at a small amount. The extent of strength improvements depends mainly on the dispersion of CNTs in the matrix and interfacial bonding between the matrix and CNTs. Limited theoretical modeling can predict the properties of CNT/Al composites to some extent, but without considering the detailed processing parameters. Based on the gaps identified here, future research directions are suggested, including the relationships between the processing parameters and micro-and nanostructures, and multiscale mechanical modeling and simulation, aiming to further understand the strengthening mechanisms and develop advanced CNT-reinforced Al and other metal composites for critical engineering applications.

The drive for increasing fuel efficiency and decreasing anthropogenic greenhouse effect via lightweighting leads to the development of several new Al alloys. The effect of Mn and Fe addition on the microstructure of Al‐Mg‐Si alloy in as‐cast condition was investigated. The mechanical properties including strain‐controlled low‐cycle fatigue characteristics were evaluated. The microstructure of the as‐cast alloy consisted of globular primary α‐Al phase and characteristic Mg2Si‐containing eutectic structure, along with Al8(Fe,Mn)2Si particles randomly distributed in the matrix. Relative to several commercial alloys including A319 cast alloy, the present alloy exhibited superior tensile properties without trade‐off in elongation and improved fatigue life due to the unique microstructure with fine grains and random textures. The as‐cast alloy possessed yield stress, ultimate tensile strength, and elongation of about 185 MPa, 304 MPa, and 6.3%, respectively. The stress‐strain hysteresis loops were symmetrical and approximately followed Masing behavior. The fatigue life of the as‐cast alloy was attained to be higher than that of several commercial cast and wrought Al alloys. Cyclic hardening occurred at higher strain amplitudes from 0.3% to 0.8%, while cyclic stabilization sustained at lower strain amplitudes of ≤0.2%. Examination of fractured surfaces revealed that fatigue crack initiated from the specimen surface/near‐surface, and crack propagation occurred mainly in the formation of fatigue striations.

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