Microstructural study and simulation of intrinsic two-way shape memory behavior of functionally graded Ni-rich/NiTiCu thin film

Journal Article · Mon Jan 15 00:00:00 EST 2018 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2017.11.056· OSTI ID:22804873

Mohri, Maryam; Taghizadeh, Milad ^[1]; Wang, Di ^[2]; Hahn, Horst ^[2]; Nili-Ahmadabadi, Mahmoud ^[1]

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1. School of Metallurgy and Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)
2. Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe 76021 (Germany)

Highlights: • Ni-rich/Ti-rich bi-layer thin film was deposited on Si by using DC magnetron sputtering. • The bi-layer exhibits the gradient structure and mechanical properties through the thickness. • The bi-layer shows intrinsic two-way shape memory effect due to functionally graded structure. • The intrinsic two-way shape memory effect was confirmed by finite element simulation. - Abstract: In this research, the gradient structure and mechanical properties of an austenitic/martensitic (Ni{sub 50.8}Ti/Ni{sub 45}TiCu{sub 5} (at.%)) bi-layer thin film was investigated. The bi-layer was deposited on a Si substrate using DC magnetron sputtering. After crystallization of the film at 773 K for 60 min, the microstructure and mechanical properties of the bi-layer thin film were characterized using X-ray diffraction (XRD), transmission electron microscopy (STEM and HRTEM) and nanoindentation, respectively. The diffraction pattern illustrated that the crystallized bi-layer was combined of martensitic and austenitic layers while secondary ion mass spectroscopy (SIMS) and high resolution transmission electron microscopy analysis demonstrated the existence of a compositional gradient through the thickness and residual strain in the interface of the bi-layer, respectively. Furthermore, the compositional gradient in the bi-layer led to gradual variations in the structure, hardness and Young's modulus through the thickness of the bi-layer. The intrinsic two-way shape memory effect due to its functionally graded structure and the induced stress was confirmed by experimental test and finite element simulation.

• OSTI ID: 22804873
• Journal Information: Materials Characterization, Vol. 135; Other Information: Copyright (c) 2017 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 1044-5803
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AUSTENITIC STEELS
COMPUTERIZED SIMULATION
COPPER COMPOUNDS
CRYSTALLIZATION
FINITE ELEMENT METHOD
HARDNESS
ION MICROPROBE ANALYSIS
LAYERS
MAGNETRONS
MARTENSITIC STEELS
MASS SPECTROSCOPY
MICROSTRUCTURE
NICKEL COMPOUNDS
SHAPE MEMORY EFFECT
SPUTTERING
THICKNESS
THIN FILMS
TITANIUM COMPOUNDS
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION