Effect of aging time on shape memory properties of sputtered Ni-rich Ni2MnGa alloy films

Motohiko Suzuki, Makoto Ohtsuka, Minoru Matsumoto, Yasukazu Murakami, Daisuke Shindo, Kimio Itagaki

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Ni2MnGa alloy is an intelligent material with ferromagnetic and shape memory properties. The application of the alloy films to microactuators has been proposed. The Ni-rich Ni2MnGa alloy films with a thickness of nearly 5 μm were deposited on Al2O3 substrates by a radio-frequency magnetron sputtering apparatus using a Ni52Mn24Ga24 target. They were heat-treated at 1073 K for 36 ks for homogenization and ordering. The martensitic transformation temperatures of the heat-treated films were higher than room temperature. To investigate the effect of aging time on shape memory properties, the heat-treated films were aged at 673 K for various times between 0.9 and 57.6 ks in a constrained condition. The constraint-aged films showed the two-way shape memory effect by thermal cycling. Fine precipitates with a crystal structure of L12 were observed in the constraint-films aged for a long period. As for their two-way shape memory properties, a range of transformation temperature narrowed and the amount of macroscopic shape change increased with increasing aging time.

Original languageEnglish
Pages (from-to)861-866
Number of pages6
JournalMaterials Transactions
Volume43
Issue number5
DOIs
Publication statusPublished - 2002 May

Keywords

  • Constraint-aging
  • Martensitic transformation
  • Nickel-manganese-gallium
  • Precipitate
  • Shape memory alloy
  • Sputter-deposition
  • Two-way shape memory effect

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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