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Nano-Impact (Fatigue) Characterization of As-Deposited Amorphous Nitinol Thin Film
College of Engineering, Alfaisal University, P.O. Box 50927, Riyadh, 11533, Saudi Arabia
School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK
Thin Film Centre, Scottish Universities Physics Alliances (SUPA), University of the West of Scotland, Paisley, PA1 2BE, UK
* Author to whom correspondence should be addressed.
Received: 14 June 2012; in revised form: 8 August 2012 / Accepted: 13 August 2012 / Published: 31 August 2012
Abstract: This paper presents nano-impact (low cycle fatigue) behavior of as-deposited amorphous nitinol (TiNi) thin film deposited on Si wafer. The nitinol film was 3.5 µm thick and was deposited by the sputtering process. Nano-impact tests were conducted to comprehend the localized fatigue performance and failure modes of thin film using a calibrated nano-indenter NanoTest™, equipped with standard diamond Berkovich and conical indenter in the load range of 0.5 mN to 100 mN. Each nano-impact test was conducted for a total of 1000 fatigue cycles. Depth sensing approach was adapted to understand the mechanisms of film failure. Based on the depth-time data and surface observations of films using atomic force microscope, it is concluded that the shape of the indenter test probe is critical in inducing the localized indentation stress and film failure. The measurement technique proposed in this paper can be used to optimize the design of nitinol thin films.
Keywords: nitinol; shape memory alloys; nano-impact; fatigue; residual stress; film failure; Berkovich; conical
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MDPI and ACS Style
Faisal, N.H.; Ahmed, R.; Fu, R.(. Nano-Impact (Fatigue) Characterization of As-Deposited Amorphous Nitinol Thin Film. Coatings 2012, 2, 195-209.
Faisal NH, Ahmed R, Fu R(. Nano-Impact (Fatigue) Characterization of As-Deposited Amorphous Nitinol Thin Film. Coatings. 2012; 2(3):195-209.
Faisal, Nadimul H.; Ahmed, Rehan; Fu, Richard (Yongqing). 2012. "Nano-Impact (Fatigue) Characterization of As-Deposited Amorphous Nitinol Thin Film." Coatings 2, no. 3: 195-209.