Molecular dynamics simulation of Cu-Al functional gradient alloys under tensile loading

JW Zhang and Q Zhao and L Zhang, SOLID STATE COMMUNICATIONS, 404, 116060 (2025).

DOI: 10.1016/j.ssc.2025.116060

Conventional research tools are difficult to reveal the relationship between nanoscale microstructural changes and macroscopic properties of functional gradient materials (FGMs), and it is not clear how the gradient composition distribution regulates the mechanical properties of alloys. To this end, the present study employed a molecular dynamics (MD) approach to systematically investigate the tensile mechanical response of Cu-Al gradient alloys with different compositional distribution functions (power-law, exponential and S-type) and to analyse the effects of strain rate and temperature on the mechanical properties of Cu-Al functional gradient alloys with S-type distribution functions. It is found that P-FGM is suitable for symmetric strengthening design, E-FGM is used for fast gradient response design, and S-FGM is outstanding in suppressing stress concentration. The Sshaped distribution function with different functional parameters can effectively delay the accumulation of dislocations and improve the deformation uniformity. As the gradient parameter p increases, the ultimate tensile strength (UTS) of the material tends to decrease and the time of the peak of dislocations is delayed, which is a phenomenon mainly attributed to the fact that the smooth gradient effectively disperses the stress concentration and reduces the risk of local failure. In addition, an increase in temperature leads to a gradual transformation of the FCC structure of Cu-Al alloys into an amorphous structure, resulting in a significant decrease in strength. While the increase in the velocity of the deformation can enhance the strength, it also causes a loss of elongation. This highlights the relationship between the enhancement of the velocity of deformation and the reduction of plasticity. The present study utilised molecular dynamics simulations to reveal the correlation between the degree of layering and the properties of plasticity. This provides a foundation for the design of functional layered alloys.

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