The micro-yield strength and coefficient of thermal expansion of nanodiamond reinforced 2024 aluminum composites

The micro-yield strength (Micro-YS) and coefficient of thermal expansion (CTE) of aluminum matrix composites are crucial factors influencing their application in inertial instruments. In this study, nanodiamond (ND) was selected as reinforcement to fabricate the ND uniformly dispersed ND/2024Al composites with varying volume fractions ranging from 0 to 1.6 vol.%. The microstructure of ND/2024Al composites was examined using SEM and TEM, and their properties were evaluated through the Micro-YS and CTE. The experimental results confirmed that the uniformly dispersed ND improved the properties of the composites by enhancing the Micro-YS and Macro-YS of the 1.6 vol.% ND/2024Al composite to 388.6 MPa and 540.7 MPa, representing a significant improvement of 40.2% and 34.4% compared to that of the 2024 aluminum alloy, respectively. Meanwhile, only a limited reduction in CTE due to the limited content of ND added. A comprehensive discussion on the strengthening mechanism was conducted.