Atomistic investigation on the conversion of plastic work to heat in high-rate shear deformation

The conversion of work into heat is one of the most significant characteristics of plastic deformation, especially in a high strain rate regime. The quantitative characterization of the fraction of plastic work converted into heat plays a crucial role in understanding the deformation process and mechanism and establishing an accurate and reasonable thermomechanical constitutive model. However, the fraction of plastic work converted into heat is experimentally found to span over a wide range of values between 0.1 and 1. In this paper, the conversion of plastic work into heat in high-rate shear deformation is systematically investigated through the relations between temperatures, stresses, elastic and plastic strains using molecular dynamics simulation. The results show that the temperature rise in the shear deformation is caused by the heat dissipation of the plastic work rather than the thermo-elastic coupling effect due to invariance of the volume. Dislocation nucleation and glide are the main mechanisms of shear deformation and are also the origins of heat generation. The continuous slip of dislocations also results in the formation of deformation twins. Interestingly, the work-to-heat conversion coefficient is revealed to be independent of crystal orientation, in contrast to the plastic deformation itself. From the present study, we conclude that almost all the plastic work in shear deformation is converted into heat dissipation for all studied samples.