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Deformation Mechanism of Amorphous/nanocrystalline Multilayer Thin Films on Polyimide Substrates

The tensile behavior of the monolithic amorphous ZrCu and crystalline Cu thin films and the ZrCu/Cu multilayered thin films, coated on polyimide (PI) substrates in different layer thicknesses has been investigated. The scanning electron microscope (SEM) morphology of the as-deposited thin film is composed of sphere domains. Between the domains, stress concentration is induced. The cracks perpendicular to the loading direction would propagate along the domains. The constituent component examined by energy dispersive X-ray spectrometer (EDS) shows that the average composition (in atomic percent) amorphous thin film is Zr46.78Cu53.22, closed to the designed Zr50Cu50 goal. The X-ray diffraction (XRD) results show that the multilayered specimens are composed of both amorphous ZrCu and nanocrystalline Cu crystal structure. As the monolayer thickness become lower, the normalized peak height and grain sizes of Cu become lower. To obtain the mechanical properties of the coated films, deducting the contribution of substrates is used in this study. The tensile Young¡¦s moduli of monolithic amorphous ZrCu and nanocrystalline Cu thin films are close to the results extracted from micro-compression. Based on the current tensile results for the moduli of multilayered thin films, the obtained mechanical data are demonstrated to be reliable and are consistent with the theoretical values predicted by Rule of Mixture. As the thickness decreases from 100 nm down to 10 nm, the tensile Young¡¦s moduli do not vary much. On the other hand, the maximum tensile stress shows strong variation, being highest for the layer thickness of 25 nm. The deformed surface morphologies characterized by scanning electron microscopy also exhibit a similar trend. The optimum tensile properties of the monolithic and multilayered thin film combinations are examined and discussed in this thesis.

Identiferoai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0905111-112348
Date05 September 2011
CreatorsHuang, Han-shen
ContributorsKao Po-We, J.C.Huang, Chen, Ming
PublisherNSYSU
Source SetsNSYSU Electronic Thesis and Dissertation Archive
LanguageEnglish
Detected LanguageEnglish
Typetext
Formatapplication/pdf
Sourcehttp://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0905111-112348
Rightsuser_define, Copyright information available at source archive

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