Thermomechanical conversion in high-rate plastic deformation of nanotwinned polycrystalline copper.

Many experiments have shown that plastic deformation of metals generates heat, leading to temperature rise of the material. However, little is known about the underlying factors that govern the heat generation, especially in polycrystalline metals involving high-rate plastic deformation. In this work, the work-to-heat conversion during high-rate plastic deformation of polycrystalline coppers with and without nanotwins is studied using molecular dynamics simulations. The results show that within a certain range of imposed deformation, smaller grain size results in higher plastic work-to-heat conversion, due to larger proportion of grain boundaries. For a given grain size of polycrystalline copper with twins, the portion of plastic work converted to heat increases as the twin-boundary spacing decreases within a certain deformation range. However, at large deformation the plastic work-to-heat conversion coefficient should be analyzed specifically for each individual sample due to the transformation of the deformation mechanism (i.e., the change of the energy storage). [ABSTRACT FROM AUTHOR]