Anomalous deformation twinning in coarse-grained Cu in Ag₆₀Cu₄₀ composites under high strain-rate compressive loading

The deformation response of a directionally solidified Ag₆₀Cu₄₀ eutectic alloy with a cube-on-cube orientation relationship between Ag and Cu subjected to high strain-rate 10³s^-1 compressive loading was examined. Loading at 45° and 90° to the growth axis, near [001] and [111-] local crystal orientations, respectively, resulted in deformation twinning and dislocation slip in both Ag and Cu under conditions where deformation twinning would not normally be expected in Cu. In contrast, loading at 0° and 90° to the growth axis, near 〈101〉 local crystal orientations, resulted in the primary deformation mode being dislocation slip. These results are interpreted in terms of the influence of loading axis with respect to the local crystal orientation in the directionally solidified alloy and on slip transmission from Ag into Cu.