Twinnability in face-centered cubic metallic solids based on electronic band structure

Twinnability in face-centered cubic metallic solids is discussed from the viewpoint of wavenumber (k) space. The 111 deformation twinning is one of the main plastic deformation modes enabling the rearrangement of a mirror-symmetry lattice structure across a twin boundary. The crystalline rearrangement around 112¯ in k-space is triggered by changes in the electron density distribution caused by the strain-induced modulation of the electronic band structure around this orientation. This modulation is defined by the twinnability, ε112¯, which reflects the difficulty of the redistribution of electron density around 112¯. This index clarifies that the deformation twinning is suppressed in aluminum (Al) due to its large ε112¯ value. This result rationalizes the disorder between platinum and Al observed in conventional twinnability assessments based on stacking fault energy.