Consolidation of amorphous Al{sub}86Ni{sub}6Co{sub}2Gd{sub}6 melt-spun ribbons by twist extrusion

摘要

Amorphous Al{sub}86Ni{sub}6Co{sub}2Gd{sub}6 ribbons produced by melt-spinning processing were consolidated using twist extrusion (TE). Electrical resistance measurements showed that under continuous heating at 5 K/min crystallization begins at 473 K by formation of Al-nanocrystals and ends at 673 K by formation of equilibrium intermetallics. From one to five TE extrusion passes were conducted in several experiments at temperatures 458-573 K and applied pressures ranged between 1150-1700 MPa. The fully dense billets with dimensions 14×23×40 mm{sup}3 were produced at extrusion temperatures ≥ 523 K. The maximum microhardness (550 kgf/mm{sup}2) was reached for the bulk materials consolidated at 523 K with a nanocomposite structure consisted of Al-nanocrystals with size about 13 nm embedded in amorphous matrix. The billet compacted at 573 K has a fully crystallized structure and lower microhardness (380 kgf/mm{sup}2).