  Slip transfer across grain boundaries was studied in annealed polycrystalline
Al foils deformed in uniaxial tension by means of the analysis of the slip
traces on the specimen surface. Grain orientations and selected grain boundary
misorientations were measured on both surfaces of the sample using electron
back-scattered diffraction mapping. It was found that most of the grains were
within 15{\deg} of a cube orientation and approximately half of the grains
percolated through the specimen thickness. The Luster-Morris m' parameter (that
can be computed from the surface grain orientation) was used to assess the
likelihood of slip transfer across boundaries. It was found that transfer
across grain boundaries was rare in near-cube oriented grains, and convincing
evidence was only found when m' > 0.97, which corresponds to low-angle
boundaries with <15{\deg} misorientation. This behavior was explained by the
presence of many active slip slips in near-cube oriented grains that favor
self-accommodation of the grain shape to the evolving boundary conditions
imposed by neighboring grains instead of promoting slip transfer across the
boundary. These results indicate that the alignment between slip planes and
slip directions across the boundary is not the only important metric to
determine the threshold for slip transfer, as the particular details of
deformation in each grain (such as the number of available slip systems) also
must be considered.
