In-Situ Observation of Transition Between Surface Relief and Wrinkling in Thin Film Shape Memory Alloys

Fu, Yong Qing, Sanjabi, Sohrab, Barber, Zoe, Huang, Wei Min, Cai, M., Zhang, Sam, Luo, J. K., Flewitt, Andrew and Milne, William (2008) In-Situ Observation of Transition Between Surface Relief and Wrinkling in Thin Film Shape Memory Alloys. Journal of Nanoscience and Nanotechnology, 8 (5). pp. 2588-2596. ISSN 1533 4880

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Abstract

Significant surface morphology evolution between relief and wrinkling was observed on a 3.5 m thick TiNiCu film sputter-deposited on a silicon substrate. At room temperature, variation in surface relief morphology (from separated martensite crystals embedded in amorphous matrix to fully inter-weaved martensite plates) was observed with slight change in film composition. The phenomenon was attributed to variations in crystallization temperatures of as-deposited amorphous films during annealing because of the compositional difference. During thermal cycling between room temperature and 100 °C, reversible surface morphology changes can be observed between surface relief and wrinkling patterns. The formation of the surface wrinkling is attributed to the large compressive stress in the film during high temperature post-annealing and crystallization, whereas surface relief is caused by the martensitic transformation to relieve the large tensile stress in the film. Compositional effect on this surface morphology evolution is discussed. Results also indicate that there is a critical dimension for the wrinkling to occur, and a small circular island can only relax by in-plane expansion.

Item Type:	Article
Uncontrolled Keywords:	Relief, shape memory, surface morphology, thin film, tinicu, wrinkling
Subjects:	F200 Materials Science
Department:	Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User:	Becky Skoyles
Date Deposited:	27 Mar 2015 10:42
Last Modified:	12 Oct 2019 19:06
URI:	http://nrl.northumbria.ac.uk/id/eprint/21885

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