Gorazd Lojen (Author), Ivan Anžel (Author), Albert C. Kneissl (Author), E. Unterweger (Author), Borut Kosec (Author), Milan Bizjak (Author)

Abstract

Cu-Al-Ni shape memory alloys (SMAs) are currently the only available high temperature SMAs, showing a good resistance against functional fatigue. In polycrystalline state, they are very brittle and exhibit, in general, only small reversible deformations. By melt spinning, thin Cu-Al-Ni ribbons can be manufactured directly from the melt. Appropriate casting parameters can ensurea single layer columnar structure with a fibre texture, which significantly increases the maximal reversible strain in longitudinal direction. Cu-Al-Ni ribbons, containing 13, 14 and 15 wt.% Al were cast by free jet melt spinning. Because of the alloys' low thermal conductivity, the cooling rate was surprisingly low - considering the crystal grain size - significantly below 103 K/s. Therefore, wide ribbons having a single layer columnar and (except the ribbons containing 13 wt.% Al) completely martensiticstructure could not be obtained. Regardless the chemical composition, the ribbons have a single layer columnar structure only if the thickness does not exceed approximately 50 m, otherwise the structure consists of at least two layers of equiaxed grains. In as-cast condition, only ribbons containing 13 wt.% Al seem to be completely martensitic. Heat treatments at temperatures up to 900 °C improved the structure of 13 and 14 wt.% Al ribbons. All ribbons exhibit one-way shape memory effect in as-cast condition. Heat-treated ribbons containing 13 wt.% Al exhibited two-way shape memory effect already after one bending and heating cycle.

Keywords

metalurgija;zlitine z oblikovnim spominom;zlitina Cu-Al-Ni;mikrostruktura;metallurgy;shape memory alloys;Cu-Al-Ni alloy;microstructure;melt spinning;

Data

Language: English
Year of publishing:
Typology: 1.01 - Original Scientific Article
Organization: UM FS - Faculty of Mechanical Engineering
UDC: 669.018
COBISS: 9607190 Link will open in a new window
ISSN: 0924-0136
Views: 1668
Downloads: 96
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Other data

Secondary language: English
Secondary keywords: metalurgija;zlitine z oblikovnim spominom;zlitina Cu-Al-Ni;mikrostruktura;
URN: URN:SI:UM:
Pages: str. 220-229
Volume: ǂVol. ǂ162/163
Chronology: May 2005
ID: 8718295