Dislocation-nanoparticle interactions in TiB2p/Cu composites based on molecular dynamics and experiments

PT Li and CX Zhao and CK Ding and YH Jiang and SH Liang and F Cao and YF Wang and J Lyu and H Shi and XD Zhang and HR Zhong and YH Pang and HX Yan and V Koval, JOURNAL OF ALLOYS AND COMPOUNDS, 1033, 181256 (2025).

DOI: 10.1016/j.jallcom.2025.181256

The Orowan mechanism is a cornerstone in strengthening metal matrix composites (MMCs), yet a detailed understanding of how dislocations bypass second-phase particles remain one of material sciences challenges for optimizing mechanical properties of MMCs. This study innovatively combines molecular dynamics (MD) simulations and experimental observations to design TiB2 particle-reinforced Cu matrix (TiB2p/Cu) composites with edge dislocations. We explore the effects of nanoparticle size and distance on dislocation interactions during the Orowan process. The results reveal that the stress field around nanoparticles significantly impedes dislocation movement, thereby markedly enhancing the mechanical properties of copper alloys. Specifically, it was found that the critical resolved shear stress (CRSS) of the TiB2p/Cu composites rises as the nanoparticle radius increases. The interaction between dislocations and nanoparticles results in transition from the Orowan loop formation to the loop pinning strengthening. Notably, when the edge dislocations bypass multiple nanoparticles, they significantly bend and form clusters of quasi-screw dislocations, which undergo cross-slip in the strengthening process. These findings significantly advance knowledge of the Orowan mechanism, offering a viable strategy for designing high-performance MMCs with tailored mechanical properties.

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