Nanoindentation of binary and ternary Ni–Ti-based shape memory alloy thin films

Muir Wood, A. J., Sanjabi, Sohrab, Fu, Yong Qing, Barber, Zoe and Clyne, Bill (2008) Nanoindentation of binary and ternary Ni–Ti-based shape memory alloy thin films. Surface and Coatings Technology, 202 (13). pp. 3115-3120. ISSN 0257 8972

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Abstract

Thin sputtered films of binary (Ni–Ti) and ternary (Ni–Ti–Hf and Ni–Ti–Cu) shape memory alloys have been subjected to nanoindentation over a range of temperature (up to 400 °C), using a small diameter spherical indenter. The load-displacement plots obtained during these experiments have been interpreted so as to reveal whether the imposed strain was being at least partly accommodated by the martensitic phase transformation, ie whether superelastic deformation was taking place. This was done by evaluating the remnant indent depth ratio (depth after unloading/depth at peak load), which is expected to have a relatively small value if superelastic deformation and recovery are significant. It is confirmed that this procedure, which has previously been validated for bulk material, can be applied to these thin films (~ 2 µm in thickness). The results indicate that ternary alloys with up to about 20 at.%Hf or 10 at.%Cu can exhibit superelastic behaviour over suitable temperature ranges.

Item Type:	Article
Uncontrolled Keywords:	Nickel–titanium; Nickel–titanium–copper; Nickel–titanium–hafnium; Thin film; Shape memory; Indentation
Subjects:	F200 Materials Science
Department:	Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User:	Becky Skoyles
Date Deposited:	27 Mar 2015 10:47
Last Modified:	12 Oct 2019 19:06
URI:	http://nrl.northumbria.ac.uk/id/eprint/21887

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