Observations of lattice curvature near the interface of a deformed aluminium bicrystal

Reported here is a study of the pattern of lattice curvature near the inter face of deformed high-purity aluminium (99.9999%) bicrystals of specified c rystallographic character (large-angle random). Curvature data are obtained from electron back-scattering diffraction pattern observations using orien tation imaging microscopy. The concept of geometrically necessary dislocati ons (GNDs) is used as the central tool in the description of the observatio ns. The samples studied were channel-die compressed perpendicular to the in terface to plastic strain levels of 0.1 and 0.3. At a strain level of 0.1 t he primary observation is the development of a pile-up of GNDs (i.e. lattic e curvature) near the interface. At the higher strain level of 0.3, however , a dramatic change in the distribution is observed. The nature of this cha nge suggests that the interface has absorbed (or emitted) some components o f the nearby GND field, with an accompanying change in the local character of the interface towards a broader dispersion of misorientation character.