Structure of AlNiGd nanocomposites with enhanced ductility produced by high pressure torsion processing

Materials Science & Engineering A, Нидерланды. 2022. Vol. 850. Article 143420.

Vasiliev S. V., Limanovskii A. I., Tkachenko V. M., Tsvetkov T. V., Svyrydova K. A., Burkhovetskii V. V., Sayapin V. N., Naumchuk O. A., A.S.Aronin, Tkatch V. I.

The fully consolidated bilayer (consisting of two amorphous Al86Ni9Gd5 melt-spun ribbons) disks with a diameter
of 5 mm were produced using unconstrained high pressure torsion (HPT) processing subjecting for 2–5 turns at
applied pressures of 2 and 4 GPa. The structure and mechanical properties of the disks as well as those of the asprepared
and heated up to 479 K ribbon samples were studied by X-ray diffraction analysis, transmission and
scanning electron microscopy, three-point bending tests and measurements of microhardness. It was established
that the heat treatment and consolidation resulted in formation of nanocomposite structures consisting of Al
nanocrystals 21 and 6 nm in size, respectively, with enhanced microhardness. It was shown that the heat
treatment of the ribbon led to a loss of the plastic strain (from 2 to 0.4%) while the consolidated disks retained
the same level of plasticity as that in the as-cast amorphous ribbon. The possible reason of the enhanced plasticity
of the nanophase composites obtained by deformation-induced crystallization was discussed.

Keywords: plasticity, hardness, grain size, Amorphous aluminum alloys, High-pressure torsion, Nanocomposite structures