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J. Phys. IV France
Volume 11, Numéro PR8, Novembre 2001
Fifth European Symposium on Martensitic Transformations and Shape Memory Alloys
Page(s) Pr8-363 - Pr8-368
Fifth European Symposium on Martensitic Transformations and Shape Memory Alloys

J. Phys. IV France 11 (2001) Pr8-363-Pr8-368

DOI: 10.1051/jp4:2001861

Structural characterisation of melt-spun Ti50Ni25Cu25 ribbons

D. Schryvers1, P.L. Potapov1, A. Ledda1 and A.V. Shelyakov2

1  Electron Microscopy for Materials Research (EMAT), University of Antwerp, RUCA, Groenenborgerlaan 171, 2020 Antwerp, Belgium
2  Moscow Engineering Physics Institute, Kashirskoe Shosse 31, 115409 Moscow, Russia

The structure of melt-spun Ti50Ni25Cu25 ribbons after various heat treatments has been studied by X-ray and TEM analyses. As-received amorphous Ti50Ni25Cu25 ribbons, when annealed at 500°C for a few minutes, crystallise into the B2 structure, which fully transforms into the orthorhombic martensite upon cooling. The X-ray scans of Ti50Ni25Cu25 ribbons annealed for 5 min. at 500°C show the well developed orthorhombic pattern, which was used for refinement of the orthorhombic martensitic structure of TiNi-Cu alloys. The refined structure of the orthorhombic martensite in TiNi-Cu alloys differs from the standard B19 type suggested previously. X-ray investigation reveals a shift of atoms in the (010)ort layers from the centro-symmetric positions towards the [00l]ort direction. The longer annealing of Ti50Ni25Cu25 ribbons at 500°C causes TiCu precipitation and results in appearance of untransformed B2 grains at room temperature. Annealing at 700°C causes Ti3Cu4 precipitation with significant Cu depletion of the matrix resulting in the appearance of the mixed orthorhombic and monoclinic martensite

© EDP Sciences 2001