A critical examination of pure tantalum processed by high-pressure torsion

Authors: Maury, N., Zhang, N.X., Huang, Y., Zhilyaev, A.P. and Langdon, T.G.

Journal: Materials Science and Engineering: A

Volume: 638

Pages: 174-182

ISSN: 0921-5093

DOI: 10.1016/j.msea.2015.04.053

Abstract:

Tantalum, a common refractory metal with body-centred cubic (BCC) crystalline structure, was processed by high-pressure torsion (HPT) at room temperature through different numbers of rotations. Significant grain refinement and high strength were achieved with a reduction in grain size from ~60μm to ~160nm and an increase in strength from ~200 to >1300MPa. Hardness measurements revealed a high level of homogeneity after 10 turns of HPT but the hardness after 10 turns was slightly lower than after 5 turns indicating the occurrence of some recovery. Tensile testing at a strain rate of 1.0×10-3s-1 gave high strengths of ~1200MPa but little or no ductility after processing through 1, 5 and 10 turns. The introduction of a short-term (15min) anneal immediately after HPT processing led to significant ductility in all samples and a reasonable level of strength at ~800MPa.

Source: Scopus