Morphology-governed lubrication mechanisms revealed by multi-cycle molecular dynamics: From reticular constraint to globular enhancement in Cu-Pb alloys

This study investigates the influence of Pb-rich secondary phase (PSP) morphology on the tribological behavior of Cu-Pb alloys by combining experimental characterization with molecular dynamics (MD) simulations. Reticular-structured (R-Alloy) and globular-distributed (G-Alloy) PSPs were fabricated based on precise composition control and characterized using high-resolution microscopy. Under continuous friction conditions, MD simulations reveal that PSP morphology critically governs lubricating film formation through distinct Pb migration mechanisms: the interconnected network in R-Alloy restricts Pb diffusion, resulting in discontinuous films, whereas G-Alloy enables directional Pb migration and the formation of uniform lubricating layers. Quantitative analysis links strain-field gradients and thermal evolution to friction stability, showing that globular PSPs promote homogeneous deformation and better heat dissipation. The strong agreement between experimental and simulation results validates the approach and demonstrates that tailoring PSP architecture—particularly toward a globular configuration—is an effective strategy for optimizing the tribological performance of self-lubricating alloys.