Frictional interactions at high velocity ductile metal interfaces

18th APS-SCCM; 24th AIRAPT

Hammerberg, J.E.^1 ; Milhans, J.L.^1 ; Ravelo, R.J.^2 ; Germann, T.C.^1

Los Alamos National Laboratory, Los Alamos

NM

87545, United States^1

Department of Physics, University of Texas - El Paso, El Paso

TX, United States^2

关键词: Critical velocities;    Crystal interfaces;    Frictional interactions;    Initial grain size;    Non-equilibrium steady state;    Nonequilibrium molecular dynamics simulation;    Sliding interfaces;    Sliding velocities;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/500/17/172003/pdf
DOI  :  10.1088/1742-6596/500/17/172003

来源: IOP

【 摘 要 】

We have examined the effect of evolution of grain morphology on the frictional force at polycrystalline Al-Al and Al-Ta interfaces as a function of grain size and sliding velocity. We present the results of 8M, 26M and 138M particle NonEquilibrium Molecular Dynamics (NEMD) simulations for grain sizes of 13 and 20 nm. Sample sizes consisted of 3×3×3 and 5×5×5 grains on each side of a sliding interface. We have considered sliding velocities from 20 to 4000 m/s. For velocities below a size dependent critical velocity above which a fluid layer forms, we find enhanced grain coarsening leading to a highly strained, graded final steady state microstructure that exhibits a dynamic morphology for times greater than 5-10 ns. We find that the frictional force is insensitive to the initial grain size distribution due to the evolution of the initial distribution to a new nonequilibrium steady state. We discuss the relationship of these results to single crystal interfaces and the mechanisms for grain size and shape evolution.