Influence of atomised powder characteristics on texture and microstructure development in extruded A1-8Fe-4Ni base alloys

The texture and microstructure of as-extruded Al-7.7Fe-4Ni and Al-8.2Fe-4.3Ni-2.8Zr (wt.%) alloys reinforced by large volume fractions (> 30 vol.%) of coherent intermetallics was studied. It is shown that the texture and microstructure developed in the as-extruded alloys is very sensitive to characteristics of the rapidly solidified powders. In particular, variations in powder microstructure and associated hardness are responsible for heterogeneous deformation which leads to the formation of a banded structure consisting of alternate coarse and fine microstructure characterised by a major [111] fibre texture of the Al-matrix. This texture of the Al-matrix is coupled to a texture of the coherent intermetallic phase. On contrast. more homogeneous deformation results in a more homogeneous microstructure with fairly random texture for both the Al and tau phases. (C) 1999 Elsevier Science S.A. All rights reserved.