twin - twin interactions can, among other things lead to incoherent twin boundaries. These cause a high energy absorption capacity, see for instance our paper:

Article Microstructure Defects Contributing to the Energy Absorption...

.... The formation of non-coherent twin boundaries or destructed twin orientation relationship infuence also in cryo-drawn copper the severely twinned microstructure, see for instance our paper:

Article Properties of cryo-drawn copper with severely twinned microstructure

Thank you Klemm...

In fcc systems, the twinning can be described by the repeated glide of 1/6 partial dislocations on {111} twin boundaries (TBs). Therefore, the twin - twin interactions in fcc systems can be described as the interaction between a twin boundary and 1/6 partial dislocations gliding on another TB.

        Now, depending on the orientation of 1/6 partial dislocations (edge, screw or any other angle) and incident angle, the twin boundary can acts as a barrier to dislocation motion (This leads to hardening) or as a slip plane (This leads to softening and increase in ductility) and it can simply transmits the incident dislocation (This causes negligible effect). This mechanisms were described in Zhu et al., Acta Mater, 2011. In addition to these mechanisms, the twin boundary can also acts as source for dislocations particularly the trailing partials (Sainath et al., Phys. Lett. A, 2015).

           Therefore the twin-twin interactions significantly influences the mechanical behaviour.

Article Dislocation–twin interactions in nanocrystalline fcc metals

Article Molecular dynamics simulation of twin boundary effect on def...

The twin-twin interactions can lead to the formation of new grain boundaries like Sigma9 and Sigma27, thus influencing the mechanical properties like flow stress etc, albeit indirectly. See our recent paper Article Atomistic mechanisms of twin–twin interactions in Cu nanopillars

Regards

Sainath