Agglomeration in two semisolid type 6082 aluminium alloys

Two 6082 aluminium alloys produced for semisolid metal forming (SSM) were i nvestigated by electron diffraction in the scanning electron microscope in order to assess the degree of particle agglomeration in the alloys. One of the alloys had been produced by grain refinement and the other by combining grain refinement and electromagnetic stirring. The investigation is based on the assumption that agglomerated particles have the same crystallographi c orientation or are related by twinning. The alloy that had been stirred s hows more low-angle grain boundaries and twin boundaries between neighbouri ng particles and thus has a higher degree of agglomeration than the unstirr ed one. This can explain some of the differences in rheological properties between the two alloys. (C) 1999 Elsevier Science S.A. All rights reserved.