Temperature-based plastic deformation mechanism of Cu/Ag nanocomposites: A molecular dynamics study

Recently, copper-silver nanocomposites (NCs) have been introduced as ideal candidates for use in medical implants owing to the antibacterial features of their constituents. Since evaluation of the mechanical properties of the implants is crucial, identification of the mechanism responsible for their plastic deformation has been a challenging issue. With respect to the fact that service operation and sterilization of these NCs are performed in high temperatures, the governing mechanism should include the role of temperature on their deformation characteristics. Accordingly, in this article, we report a series of MD-based tensile tests performed at different temperatures ranging from 1 to 600 K to assess the issue. It is demonstrated that increasing the temperature can substantially reduce the yield strength and Young's modulus of the NC sample. To reveal the temperature-based underlying mechanism, dislocation extraction analysis is implemented to identify the type and extent of dislocations in each case. Results show that due to the lack of adhesion to the copper matrix, presence of silver nanoparticles has a significant effect on the nucleation of dislocations that weakens the mechanical properties of the NC sample. It is also observed that at low temperatures, plastic deformation is followed by twining. As the temperature rises, as a result of the supply of thermal energy required for diffusion, the process of dislocation climb is accelerated. Consequently, the amount of partial dislocations as well as the extent of stacking faults is reduced providing more chances for creation and gliding of perfect dislocations. (C) 2017 Elsevier B.V. All rights reserved.