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

摘要

Al_(89)Gd_7Ni_3Fe_1 alloy powder produced by gas atomization was consolidated using equal channel angular extrusion (ECAE) and direct extrusion. The powder particle size was below 30 jxm and the as-received powder was ~70-80 percent amorphous. ECAE compaction of loose powder was conducted at 200 deg C. 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 450 deg C. After compaction at 210 deg C, the material was about 70 percent amorphous and it had 98-99 percent of the theoretical density. A fully dense alloy with a nanocrystalline structure (grain size ~700 run) was produced after extrusion at 450 deg C. Extrusion at 250 and 400 deg C led to poor consolidation of the powder due to formation of brittle intennetallic phases with volume fraction of about 40 percent.