Shape memory effect of sputtered Ni-rich Ni2MnGa alloy films aged in constraint condition

Citation
S. Isokawa et al., Shape memory effect of sputtered Ni-rich Ni2MnGa alloy films aged in constraint condition, MATER TRANS, 42(9), 2001, pp. 1886-1889
Citations number
8
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Material Science & Engineering
Journal title
MATERIALS TRANSACTIONS
ISSN journal
1345-9678 → ACNP
Volume
42
Issue
9
Year of publication
2001
Pages
1886 - 1889
Database
ISI
SICI code
1345-9678(200109)42:9<1886:SMEOSN>2.0.ZU;2-I
Abstract
The intermetallic compound Ni2MnGa has a shape memory effect and a ferromag netic property. Films of this compound may be applied for an actuator of mi cro-machines. The Ni-rich Ni2MnGa films with a nearly 5 mum thickness were deposited on an Al2O3 substrate by a radio-frequency magnetron sputtering a pparatus with a Ni52Mn24Ga24 target. The sputtering power was 400W and the substrate temperature was kept at 323 K by cooling water. The composition o f the deposited films was Ni-23.4 mol%Mn-23.0 mol%Ga. They were annealed at 1073 K for 36 ks for homogenization and ordering, and slowly cooled down i n the furnace. Martensitic transformation temperatures of the films were me asured by a differential scanning calorimeter. and the results were M-s = 3 15 K, M-f = 311 K, A(s) = 316 K and A(f) = 321 K. To induce a shape memory effect, the annealed films were aged at 573-773 K for 0.9-3.6 ks in a const rained condition. It was found that they showed the two-way shape memory ef fect by thermal cycling.