Compaction of amorphous aluminum alloy powder by direct extrusion and equal channel angular extrusion

Al89Gd7Ni3Fe1 alloy powder produced by gas atomization was consolidated using equal channel angular extrusion (ECAE) and direct extrusion. The powder particle size was below 30 mum and the as-received powder was similar to70-80% amorphous. ECAE compaction of loose powder was conducted at 200degreesC. The microstructure of the compacted material was studied after different levels of ECAE deformation, which allowed analysis of the mechanism of particle interactions, deformation and bonding during different stages of consolidation. Direct extrusion compaction was conducted at 210, 250,400, and 450degreesC. After compaction at 210degreesC, the material was about 70% amorphous and it had 98-99% of the theoretical density. A fully dense alloy with a nanocrystalline structure (grain size similar to700 nm) was produced after extrusion at 450degreesC. Extrusion at 250 and 400degreesC led to poor consolidation of the powder due to formation of brittle intermetallic phases with volume fraction of about 40%. (C) 2004 Elsevier B.V. All rights reserved.