Consolidation of Amorphous Aluminum Alloy Powder by Equal Channel Angular Extrusion
Semi-amorphous aluminum alloy powders produced by gas atomization were compacted using equal channel angular extrusion (ECAE) in the temperature range of 200-300°C. Microstructures of the compacts were studied after different levels of ECAE deformation, which allowed analysis of the mechanism of particle interactions, deformation and bonding during different stages of consolidation. Very non-homogeneous deformation of the compacted material was detected. At the temperatures of compaction, amorphous powder particles were much softer than fully crystalline powder particles, and they were severely deformed while the crystalline particles remained nearly spherical. Almost full consolidation occurred in regions predominantly consisting of amorphous and semi-amorphous powder particles at true strains of ~2. However, further excessive deformation led to strain localization and shear crack formation in the consolidated regions. Regions dominated by fully crystalline spherical particles with brittle intermetallic phases showed poor consolidation due to particle rotations and particle fracture; leading to weak particle bonding. The results show that consolidation is impeded by the presence of fully crystalline particles in the powder.
Marcello Cabibbo and Stefano Spigarelli
O.N. Senkov "Consolidation of Amorphous Aluminum Alloy Powder by Equal Channel Angular Extrusion", Materials Science Forum, Vols. 604-605, pp. 155-162, 2009