Interaction between a screw dislocation and stacking faults in FCC metals

The mechanical properties of polycrystalline metals greatly depend on the interaction between lattice dislocation and planar defects, but some details about this interaction still need to be explored. In this paper, we investigated the impingement of a screw dislocation on intrinsic stacking fault (SF) and extrinsic stacking faults (ESF) in different FCC metals by using the molecular dynamics simulations. As a screw dislocation approaches a SF from one side, the response of SF will be one of the results: (1) annihilated; (2) transformed into ESF; (3) penetrated. Also, as a screw dislocation interacts with ESF, the response of ESF will be one of the results: (1) transformed into a three-layer thick twin; (2) into an SF; (3) penetrated. Dimensionless parameters relevant to the planar fault energies and their ratios are used to predict the propensity to different interaction modes. The results reveal the evolution law of internal defects clearly, which will be significant to further understand the details of plastic deformation and to seek the underlying techniques for strengthening metals.

As a screw dislocation approaches an intrinsic stacking fault (SF) from one side, the SF may be: (1) annihilated; or (2) transformed into an extrinsic stacking fault; or (3) penetrated. Meanwhile, as a screw dislocation interacts with an extrinsic stacking fault (ESF), the ESF may be: (1) transformed into a three-layer thick twin; or (2) transformed into an SF; or (3) penetrated.Figure optionsDownload as PowerPoint slideHighlights
► We study the impingement of screw dislocation on intrinsic/extrinsic stacking fault.
► Six interaction modes have been identified.
► We analyze the resistance to, and establish the criterion for, each mode.
► We reveal the critical shear stresses for the transition among different modes.