NUCLEATION OF RECRYSTALLIZED GRAINS FROM CUBE BANDS IN HOT DEFORMED COMMERCIAL PURITY ALUMINUM

The present work was initiated in order to obtain a better understandi ng of the nucleation mechanism of cube oriented grains during recrysta llisation of hot deformed aluminium. Investigations included: the stab ility aspect of cube oriented grains during deformation, a characteris ation of cube oriented areas in the as deformed condition, and partly recrystallised states. Commercial purity aluminium, plane strain compr essed at various deformation conditions, was investigated mainly using the electron backscattering pattern (EBSP) technique in a scanning el ectron microscope (SEM). The following deformation and nucleation patt ern was observed: cube oriented grains present in the starting materia l remain orientation metastable during deformation and are smeared out to bands. The cube bands have a unique subgrain size distribution wit h a long tail towards large subgrains, making them potent nucleation s ites. The observed preferred nucleation from cube bands surrounded by the S deformation texture component, is discussed both in terms of a m icrogrowth selection mechanism and differences in stored energy betwee n the cube and S oriented regions. (C) 1996 The Institute of Materials .