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 journalArticlepeer-review

18 Citations (Scopus)


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
Issue number5
Publication statusPublished - May 2002
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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