Energy barriers associated with slip–twin interactions

Abstract

The energetics of slip-coherent twin boundary (CTB) interactions are established under tensile deformation in face centered cubic (fcc) copper with molecular dynamics simulations, exploring the entire stereographic triangle. The CTBs serve as effective barriers in some crystal orientations more than others, consistent with experimental observations. The resulting dislocation structures upon slip-twin reactions are identified in terms of Burgers vector analysis. Visualization of the dislocation transmission, lock formation, dislocation incorporation to twin boundaries, dislocation multiplication at the matrix-twin interface and twin translation, growth, and contraction behaviors cover the most significant reactions that can physically occur providing a deeper understanding of the mechanical behavior of fcc alloys in the presence of twin boundaries. The results make a distinction between deformation and annealing twins interacting with incident dislocations and point to the considerable role both types of twins can play in strengthening of fcc metals.

High temperature fatigue crack growth of Haynes 230

“…Dislocation interactions with the microstructure features, whether these are grain/twin boundaries or defects, control the slip irreversibility during a fatigue cycle. This occurs when dislocations interact with boundaries and a residual dislocation is left within that boundary [40]. Certain types of boundaries can play a significant role in increasing the resistance to fatigue crack growth and have been the focus of "grain boundary engineering".…”

Interaction mechanisms of screw dislocations with and twin boundaries in Mg

“…The interactions where residual dislocations are generated, corresponding to (2) and (3), are complicated. In the cases, the energy barrier is a determinant factor [52][53][54]. On the other hand, for screw dislocations, the interactions with the TB are only (1) and (4), that is, simple transmission and simple absorption of the slip dislocations [34,51,55].…”

Fatigue crack initiation in Hastelloy X – the role of boundaries

“…The basis for the molecular dynamics calculations for transmission, nucleation at the grain boundaries and energy barriers for glide has been described in Ref. 50 . We demonstrate (via schematics) only the cases for interaction with Σ3 boundaries in Table 1.…”