Forest hardening and Hirth lock during grinding of copper evidenced by MD simulations

Through the use of molecular dynamics (MD) simulation, grinding process of a single crystal copper with two scratch configurations (i) near spacing (NS) between adjacent scratches, and (ii) far spacing (FS) between adjacent scratches were simulated and compared to the control sample i.e., a single scratch (SS). FS configuration revealed the highest material removal, whereas NS configuration showed that the material removal is affected by various types of defects in the sub-surface which include FCC intrinsic stacking fault, a coherent twin boundary next to an intrinsic stacking fault and two adjacent intrinsic stacking faults. The formation of a Stair-rod 1/6 〈1 1 0〉 due to the reaction between two Shockley partial dislocations 1/6 〈1 1 2〉 was seen as a distinct feature of the NS configuration which forms the onset of hardening.