MICROSCOPIC OBSERVATIONS OF GLIDE IN NON CLOSE-PACKED PLANES IN ALUMINUM, AND COMPARISON WITH MAGNESIUM

Glide in non-compact planes (or non-close packed planes) is a new dislocation mechanism which plays an important role in the plasticity of f.c.c. metals like aluminum. The authors give the results of in situ experiments performed in order to determine the corresponding microscopic process. It is possible to find an orientation which allows NC glide to be observed provided the local stress tensor can be perfectly controlled in the thin foil. This condition being fulfilled in a small area, it is concluded that non-compact glide occurs by a Peierls mechanism as in the case of prismatic glide in h. c.p. magnesium. The analogy between aluminum and magnesium is supported by observations which allow the properties of the macroscopic deformation curves and slip lines in aluminum to be interpreted as the total replacement of {111} glide by non-compact glide as soon as the latter is initiated.