Stress induced crystallization of amorphous materials and mechanical properties of nanocrystalline materials: a molecular dynamics simulation study

The deformation behavior of amorphous and nanocrystalline pure Ni thin films has been investigated using a molecular dynamics simulation study based on a semi-empirical interatomic potential (MEAM). It was observed that a tensile stress introduced to an amorphous material can enhance crystallization which eventually serves as an important deformation mechanism. After completion of crystallization, grains grow mainly by the rotation and coalescence, and with increasing grain size, the flow stress also increases. It was also found that when the grain size is small (below about 3 nm), the dominant deformation mechanisms are the grain rotation and the grain boundary sliding, the former being more active for smaller grains. The dependence of these observations on the interatomic potential used in the simulation is also discussed.