Atomic-scale insights into the microscopic strengthening mechanisms of aluminum matrix composite during uniaxial tension deformation via molecular dynamics simulations

YH Zhao and R Wang and L Chen and XS Kong and YJ Guan and JW Tang, JOURNAL OF MANUFACTURING PROCESSES, 152, 1295-1309 (2025).

DOI: 10.1016/j.jmapro.2025.08.068

Incorporating reinforced particles into Al matrix is a crucial approach to enhance the mechanical properties, while the relevant microscopic strengthening mechanisms have not been clarified due to the reliance on the idealized models, single parameter consideration, and insufficient analysis. Here, an atomic-scale structural model of particle reinforced Al matrix (Si3N4/Al) composite was developed. This model not only captures the structural characteristics of real composite, but also enables more accurate simulations of tension deformation behaviors. The results show that Si3N4 particles enhance both Young's modulus and ultimate tensile strength of the composite through load transfer and dislocation pinning effects, while the particles also lead to the interface debonding and premature fracture due to the hindrance of dislocation slip and the formation of voids. The increase of particle volume fraction can exert a strong load transfer and dislocation pinning effect, but induces a dense strain network that accelerates the void coalescence, reducing the failure strain. Large-sized particles enhance the Young's modulus by bearing high load, but reduce the ultimate tensile strength and failure strain due to the weak load transfer, limited dislocation pinning, and localized strain concentration. The distribution uniformity of particles mainly affects the failure process. Low distribution uniformity has a negligible effect on the Young's modulus but promotes particle agglomeration, which restricts the dislocation motion and accelerates the void growth, thereby reducing the ultimate tensile strength and failure strain. These findings provide a theoretical foundation and practical guidance for the design and property optimization of particle reinforced metal matrix composites.

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