Texture and microstructure in very fine grain Al–Al 3 Ti alloys obtained by extrusion of mechanically alloyed powders

Abstract

Texture has been investigated in warm extruded Al–Al₃Ti bars obtained from mechanically alloyed powders. The effects of various high volume fractions of Al₃Ti phase (9, 18, and 27 vol.-%) and the very fine grain sizes that can be obtained via the mechanical alloying processing route are described. Increasing the volume fraction of Al₃Ti phase tends to decrease the anisotropy of the extruded product. The ‘conventional’ aluminium texture characterised by a predominant 〈111〉_Al fibre usually present in extruded bars is replaced at high volume fraction of Al₃Ti particles (27%) and small size of aluminium grains (300 nm) by a weak and broad 〈441〉_Al fibre. This is suggested to be associated with a modification of the predominant deformation mechanism, changing from dislocation slip towards grain boundary sliding at small grain size.