Coarsened third body grains alleviate sliding between pure nanocrystalline surfaces

Numerous applications based on iron-carbon solids such as steel alloys could benefit from a more fundamental understanding of the nanoscale mechanisms dictating friction and wear in order to improve product performance and lifetime. This communication [1] reports Resuls from large scale atomistic simulations of nanocrystalline iron systems encompassing hundreds of nanograins and millions of atoms. The constructed models capture the sliding interface plasticity and bring forth distinct mechanisms involved in friction and wear between nanocrystalline iron surfaces such as dislocation nucleation and arrest; twin boundary nucleation and propagation; grain growth, rotation and elongation; as well as grain boundary annealing and migration. The simulations will demonstrate that pure iron nanocrystalline systems prefer to coarsen interface grains while iron-carbon systems tend to develop amorphous and/or coarsened grain boundary layers in order to accommodate the sliding induced plastic deformation.