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Title: Crystallization study of amorphous sputtered NiTi bi-layer thin film

The crystallization of Ni-rich/NiTiCu bi-layer thin film deposited by magnetron sputtering from two separate alloy targets was investigated. To achieve the shape memory effect, the NiTi thin films deposited at room temperature with amorphous structure were annealed at 773 K for 15, 30, and 60 min for crystallization. Characterization of the films was carried out by differential scanning calorimetry to indicate the crystallization temperature, grazing incidence X-ray diffraction to identify the phase structures, atomic force microscopy to evaluate surface morphology, scanning transmission electron microscopy to study the cross section of the thin films. The results show that the structure of the annealed thin films strongly depends on the temperature and time of the annealing. Crystalline grains nucleated first at the surface and then grew inward to form columnar grains. Furthermore, the crystallization behavior was markedly affected by composition variations. - Highlights: • A developed bi-layer Ni45TiCu5/Ni50.8Ti was deposited on Si substrate and crystallized. • During crystallization, The Ni{sub 45}TiCu{sub 5} layer is thermally less stable than the Ni-rich layer. • The activation energy is 302 and 464 kJ/mol for Cu-rich and Ni-rich layer in bi-layer, respectively.
Authors:
 [1] ;  [2] ;  [1] ;  [3] ;  [4]
  1. School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)
  2. (Germany)
  3. (Iran, Islamic Republic of)
  4. Karlsruhe Institute of Technology, Institute of Nanotechnology, 76021 Karlsruhe (Germany)
Publication Date:
OSTI Identifier:
22476086
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Characterization; Journal Volume: 103; Other Information: Copyright (c) 2015 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALLOYS; AMORPHOUS STATE; ANNEALING; ATOMIC FORCE MICROSCOPY; CALORIMETRY; CROSS SECTIONS; CRYSTALLIZATION; LAYERS; MAGNETRONS; NICKEL; PRECIPITATION; SHAPE MEMORY EFFECT; SPUTTERING; SUBSTRATES; TEMPERATURE RANGE 0273-0400 K; THIN FILMS; TITANIUM; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION