Abstract
The microstructural evolution in the near-surface regions of a dry sliding interface has considerable influence on its tribological behavior and is driven mainly by mechanical energy and heat. In this work, we use large-scale molecular dynamics simulations to study the effect of temperature on the deformation response of FCC CuNi alloys of several compositions under various normal pressures. The microstructural evolution below the surface, marked by mechanisms spanning grain refinement, grain coarsening, twinning, and shear layer formation, is discussed in depth. The observed results are complemented by a rigorous analysis of the dislocation activity near the sliding interface. Moreover, we define key quantities corresponding to deformation mechanisms and analyze the time-independent differences between 300 K and 600 K for all simulated compositions and normal pressures. Raising the Ni content or reducing the temperature increases the energy barrier to activate dislocation activity or promote plasticity overall, thus increasing the threshold stress required for the transition to the next deformation regime. Repeated distillation of our quantitative analysis and successive elimination of spatial and time dimensions from the data allows us to produce a 3D map of the dominating deformation mechanism regimes for CuNi alloys as a function of composition, normal pressure, and homologous temperature.
Highlights
Received: 9 December 2020 Accepted: 22 December 2020 Published: 25 December 2020Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.Copyright: c 2020 by the authors
Even more important is the understanding of the mechanisms and the synergies between factors that affect microstructural evolution and in turn the system response during operation, such as temperature, load, stacking fault energy, and grain size
We used large-scale molecular dynamics simulations for the first time to explore the joint influence of temperature, applied load, and material composition on the tribological response of FCC alloys subjected to dry sliding against a rough surface
Summary
Received: 9 December 2020 Accepted: 22 December 2020 Published: 25 December 2020Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.Copyright: c 2020 by the authors. It has been frequently shown that nanocrystalline regions close to a tribologically loaded contact exhibit grain coarsening, whereas coarse-grained materials usually undergo grain refinement in the near-surface zones [3,6,7,8]. In this context, it has been demonstrated that the grain size tends to an equilibrium value, which is linked to energy minimization and depends on the contact conditions such as contact stress [3,9]. The tribological properties depend on the initial microstructure, but largely on the modified microstructure in the near-surface zones
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