Shear accommodation in dirty grain boundaries
Group for Simulation and Theory of Atomic-Scale Material Phenomena (stAMP), Department of Mechanical and Industry Engineering, Northeastern University - Boston, MA 02115, USA
Received: 22 March 2014
Accepted: 31 March 2014
The effect of solutes (dirt) on the mechanics of crystalline interfaces remains unexplored. Here, we perform atomic-scale simulations to study the effect of carbon segregation on the shear accommodation at select grain boundaries in the classical α-Fe/C system. For shear velocities larger than the solute diffusion rate, we observe a transition from coupled motion to sliding. Below a critical solute excess, the boundaries break away from the solute cloud and exhibit in a coupled motion. At smaller shear velocities, the extrinsic coupled motion is jerky, occurs at relatively small shear stresses, and is aided by fast convective solute diffusion along the boundary. Our studies underscore the combined effect of energetics and kinetics of solutes in modifying the bicrystallography, temperature and rate dependence of shear accommodation at grain boundaries.
PACS: 61.72.Mm – Grain and twin boundaries / 68.35.Dv – Composition, segregation; defects and impurities / 62.20.Hg – Creep
© EPLA, 2014