Twin stability in highly nanotwinned Cu under compression, torsion and tension

Twin stability under four distinct mechanical loading states has been investigated for highly nanotwinned Cu containing parallel nanotwins ∼40 nm thick. Observed deformation-induced microstructural changes under tension, compression, tension–tension fatigue and torsion are qualitatively compared in order to assess twin stability as a function of the loading direction and stress. It is observed that the twins are very stable although small microstructural changes vary with deformation mode. Shear bands, deformation-induced grain growth and detwinning are also discussed.