Mechanical properties of TiNbTa single crystals at cryogenic temperatures

Journal Article · Fri May 01 04:00:00 EDT 1998 · Acta Materialia

DOI:https://doi.org/10.1016/S1359-6454(97)00475-8· OSTI ID:616451

Kawabata, Takeshi ^[1]; Kawasaki, Satoshi ^[2]; Izumi, Osamu ^[3]

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1. ATOM Materials Research Lab., Sendai (Japan)
2. Honda Research and Development Co. Ltd., Tochigi (Japan)
3. Tohoku Univ., Sendai (Japan). Inst. for Materials Research

Mechanical properties of b.c.c. TiNbTa alloy single crystals, which have excellent superconducting properties, were studied by compression tests at cryogenic temperatures. A {l_brace}332{r_brace} twin occurred at 4.2 K in the as-annealed specimens of alloy 1 (Ti-40.3Nb-13.3Ta in wt%) at {chi} = {minus}15{degree} and alloy 2 (Ti-26.4Nb-34.2Ta in wt%) at {chi} = 0{degree} in which slip deformation also occurred. The specimens with other orientations in alloys 1 and 2 at 4.2 K and whole orientations at 77 and 290 K deformed by {l_brace}112{r_brace} slip. ({bar 1}01) slip was not observed. Curves of the yield or twinning stress vs {chi} at 4.2 and 77 K were different from those of typical b.c.c. metals and alloys. A new dislocation model for the {l_brace}332{r_brace} twinning mechanism is proposed whereby that after a pair of stacked twinning dislocations move, shuffling of an atomic group consisting of three atoms occurs, forming one elementary twinned layer of four {l_brace}332{r_brace} planes. This model could well explain the shape of the twin. The analysis of the twin interface coincides with observations of dense dislocation structures within the twin and on the twin interfaces.

• OSTI ID: 616451
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 8 Vol. 46; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
DISLOCATIONS
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
MICROSTRUCTURE
NIOBIUM ALLOYS
TANTALUM ALLOYS
TEMPERATURE RANGE 0000-0013 K
TEMPERATURE RANGE 0065-0273 K
TITANIUM ALLOYS
TWINNING