High entropy alloy nanocomposites produced by high pressure torsion

(a) Taheriniya Shabnam, (a) A. Davani Farnaz, (a) Hilke Sven, (b) Hepp Marco, (c) Gadelmeier Christian, (d) Chellali Mohammad Reda, (e) Boll Torben, (a) Rösner Harald, (a) Peterlechner Martin,(f) Gammer Christoph,(a) Divinski Sergiy V.,(b) Butz Benjamin,(c) Glatzel Uwe,(d) Hahn Horst,(a) Wilde Gerhard

Abstract

High-pressure torsion was applied to join two disks of single-phase equiatomic fcc CoCrFeMnNi and bcc HfNbTaTiZr high entropy alloys (HEAs). After 15 revolutions a bulk nanocomposite had developed with alternating nano-lamellae of elongated nanocrystalline CoCrFeMnNi and mixed amorphous-nanocrystalline HfNbTaTiZr, exhibiting complex microstructures with numerous vortex-like regions. While the fcc phase retains a rather homogeneous elemental distribution, the former bcc high entropy alloy experiences a chemical separation towards Ta-rich and Ta-poor phases. The joining of dissimilar HEAs under constrained conditions (cold shut) enables the design of novel HEA-based composites by non-equilibrium processing.