Two-way shape memory effect of ferromagnetic Ni-Mn-Ga sputter-deposited films

Makoto Ohtsuka, Minoru Matsumoto, Kimio Itagaki

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

The ternary Ni2MnGa intermetallic compound is an intelligent material which has both a ferromagnetic property and a shape memory effect (SME). The use of the shape memory alloy films for an actuator of micro-machines is very attractive because of its large recovery force. The purpose of the present study is to investigate the effects of fabrication conditions and to clarify the relationships between these properties and fabrication conditions of the Ni-Mn-Ga films. The Ni-Mn-Ga films with a thickness of nearly 5 μm were deposited with a radio-frequency magnetron sputtering apparatus using a Ni50Mn25Ga25 or Ni52Mn24Ga24 target. They were heat-treated at various temperatures between 873 and 1273 K for homogenization and ordering and then cooled in a furnace. The composition of the films depended on the sputtering power. The as-deposited films were crystalline and had columnar grains. After the heat treatment the grains widened and the grain boundary became indistinct with the increasing heat treatment temperature. The martensitic transformation temperature of the heat-treated films increased with increasing nickel content. Furthermore the effect of plastic deformation and constraint aging on SME is also investigated. After plastic deformation, the two-way SME was shown through the martensitic transformation and its reversion. The intensity of X-ray diffraction peaks from stress-induced martensitic phase was found. The constraint-aged films also showed the two-way SME by thermal cycling.

Original languageEnglish
Title of host publicationYazawa International Symposium
Subtitle of host publicationMetallurgical and Materials Processing: Principles and Techologies; Materials Processing Fundamentals and New Technologies
EditorsF. Kongoli, K. Itagaki, C. Yamauchi, H.Y. Sohn, F. Kongoli, K. Itagaki, C. Yamauchi, H.Y. Sohn
Pages1213-1226
Number of pages14
Publication statusPublished - 2003 Oct 16
EventYazawa International Symposium: Metallurgical and Materials Processing: Principles and Technologies; Materials Processing Fundamentals and New Technologies - San Diego, CA, United States
Duration: 2003 Mar 22003 Mar 6

Publication series

NameYazawa International Symposium: Metallurgical and Materials Processing: Principles and Techologies; Materials Processing Fundamentals and New Technologies
Volume1

Other

OtherYazawa International Symposium: Metallurgical and Materials Processing: Principles and Technologies; Materials Processing Fundamentals and New Technologies
CountryUnited States
CitySan Diego, CA
Period03/3/203/3/6

ASJC Scopus subject areas

  • Engineering(all)

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