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

Yong Qing Fu, Sohrab Sanjabi, Zoe Barber, Wei Min Huang, M. Cai, Sam Zhang, J. K. Luo, Andrew Flewitt, William Milne

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

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.
Original languageEnglish
Pages (from-to)2588-2596
JournalJournal of Nanoscience and Nanotechnology
Volume8
Issue number5
DOIs
Publication statusPublished - 1 May 2008

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