ESOMAT 2009, 02016 (2009)
DOI: 10.1051/esomat/200902016

The structure and functional properties of Ni–Ti–Cu alloy rapidly quenched ribbons with different parts of crystalline phase

Belyaev S. P.¹, Istomin-Kastrovskiy V. V.², Koledov V. V.³, Kuchin D. S.³, Lega P. V.³, Resnina N. N.¹, Shavrov V. G.³ and Shelyakov A. V.<sup>4

1</sup>  Saint-Petersburg State University, 7-9, Universitetskaya nab., St. Peterburg, 199034, Russian Federation.
²  State Technological University “Moscow Institute of Steel and Alloys”, 119049, Moscow, Lenin av., 4, Russian Federation.
³  Kotelnikov’ Institute of Radio-engineering and Electronics of Russian Academy of Sciences, 125009, Moscow, Mohovaya st., 11/7, Russian Federation.
⁴  The Moscow engineering-physical institute, 115409, Moscow, Kashirskoe Highway, 31, Russian Federation.

rexby@list.ru

Published online: 1 September 2009

Abstract
The structure and thermomechanical properties of Ni-Ti-Cu alloy partially crystallized rapidly quenched ribbons were studied. The technique of controlled isothermal annealing of the initially amorphous ribbons in the differential scanning calorimeter was used for preparation of the samples with determined relations of extracted thermal energies to the full crystallization energy. The thermomechanical properties of the ribbons were studied in temperature interval -100..100 C. It was found that temperature dependence of bending deformation demonstrates hysteresis for the samples with more then 29% of crystalline phase. The shape memory effect manifests itself in these samples. The value of the reversible strain rises with the crystalline phase increase. The HRTEM studies show that rare crystallites have spherical shape in samples with 15% crystalline phase. Their sizes vary from 100 to 1000 nm. The DSC studies show peaks corresponding to the direct and reverse martensitic transformation at temperatures T_am = 15 C and T_ma = 29 C. The concretion of crystallites with plane boundaries formation was observed in samples with 29% of crystalline phase. The martensitic transformation is suppressed in crystallites less than 300 nm at room temperature. Unlike this in big (~ 1 μm) crystallites the structure of martensitic twins were observed. The transition zone between crystal and amorphous phases of the alloy on crystallites’ boundaries was studied by HRTEM technique. The model for the explanation of the observed phenomena is discussed.

© Owned by the authors, published by EDP Sciences 2009