High-strength Al matrix composites reinforced with uniformly dispersed nanodiamonds.

• NDs are uniformly dispersed in the matrix by a surface modification strategy. • NDs are intimately contacted with the matrix, forming stable, low-indexed interfaces. • A high tensile strength of 741.1 MPa was achieved for 0.8 vol% ND/2024Al composite. • The strengthening mechanisms of ND/2024Al composites are clarified. Poor dispersion of nanodiamonds (NDs) is the bottleneck to exploit their intrinsically excellent properties in metal matrix composites (MMCs). In this study, a strategy of surface modification was developed to uniformly disperse ND particles into 2024 aluminum alloy. Microstructure observations showed that individual NDs are closely contacted with the matrix, forming reaction-free interfaces. Consequently, a high-strength 0.8 vol% ND/2024Al composite with an ultimate tensile strength of 741.0 MPa is developed. Theoretical and experimental measurements prove that the strength improvement of ND/2024Al composite is mainly attributed to the Orowan strengthening, thermal mismatch strengthening and grain refinement strengthening. This work demonstrates the effective application of NDs as a reinforcement for MMCs towards high-specific-strength materials. [ABSTRACT FROM AUTHOR]