The fabrication of high strength Zr/Nb nanocomposites using high-pressure torsion.

Abstract

Nanocomposites of Zr/Nb with exceptionally high hardness were fabricated successfully through the high-pressure torsion (HPT) processing of prepacked Nb/Zr/Nb sandwich samples at ambient temperature. The initial layers of Nb and Zr became fragmented during HPT processing with the formation of many fine-scale intermixed Zr/Nb layers. The intermixing of these Zr/Nb layers increased both with increasing HPT revolutions from 10 to 100 and with increasing radial positions on the disks. The Vickers microhardness, Hv, increased with increasing revolutions and with radial position reaching a maximum of ~700 Hv at the edge of the 100 turns sample. Exceptional grain refinement to the range of ~20 to 40 nm and the occurrence of twinning were associated with the HPT-processed Zr/Nb composites after 100 turns. These results suggest a potential route for fabricating high strength bulk Zr/Nb nanocomposites.