Tensile Tests of Various Thin Films

2008 ◽  
pp. 229-229-19 ◽  
Author(s):  
WN Sharpe ◽  
KM Jackson ◽  
G Coles ◽  
MA Eby ◽  
RL Edwards
Keyword(s):  
1995 ◽  
Vol 403 ◽  
Author(s):  
D. van Heerden ◽  
D. Josell ◽  
D. Shechtman

AbstractAlthough mechanical studies of multilayer thin films are increasingly more abundant, the majority of studies merely determine film hardness using micro- or nanoindentation techniques. Actual tensile tests are still quite rare. We have therefore conducted tensile tests of free standing aluminum-titanium multilayer thin films. This system was selected for its potential use as a low density (3.3 g/cm3) structural material with potential aerospace applications. The strongest multilayers produced, with bilayer thicknesses 7nm Ti/16 nm Al, fractured at tensile stresses (UTS) of 900 MPa - well beyond the UTS of either of the constituent materials. Specimen characterization by xray diffraction as well as transmission electron microscopy (TEM) revealed near perfect texturing and an intriguing hcp to fec transformation of the titanium layers during preparation of samples for TEM viewing.


1998 ◽  
Vol 13 (10) ◽  
pp. 2902-2909 ◽  
Author(s):  
D. Josell ◽  
D. van Heerden ◽  
D. Read ◽  
J. Bonevich ◽  
D. Shechtman

Yield stresses, ultimate tensile strengths, and specific strengths of aluminum/titanium multilayer thin films are determined from the results of uniaxial tensile tests. The plasticity in the stress-strain curves, the nature of the fracture surfaces, and the relationship of the yield stress and the bilayer thickness are discussed. Properties are compared with those of other multilayer materials published in the literature.


1998 ◽  
Vol 518 ◽  
Author(s):  
D. T. Read

AbstractThe silicon-framed tensile specimen design has been used in tensile tests of thin films of a variety of metals and epitaxial silicon. A piezo-actuated microtensile test device holds the specimen while the silicon frame is cut just before testing, imposes the tensile displacement, and provides voltages proportional to force and displacement. This technique is appropriate for films that are hundreds of micrometers long, tens to a few hundred micrometers wide, and from 0.3 to 15 micrometers thick. The specimen film must be amenable to lithographic patterning, must adhere well to the silicon substrate, and must resist a silicon etchant. The specimen fabrication is a bulk-micromachining process, because the silicon substrate is etched through underneath the specimen film. Uniaxial yield strength, ultimate tensile strength, and elongation to maximum load can be measured using the microtensile tester. The addition of laser illumination and digital photography allows implementation of electronic speckle pattern interferometry, for accurate measurement of local displacement. This addition allows evaluation of the tensile Young's modulus. Compared to bulk material, thin films of copper and aluminum have lower apparent Young's moduli, higher yield and ultimate tensile strengths because of their fine grain size, and lower elongation to failure. Correlation between properties measured by indentation and by tensile testing needs further study.


2011 ◽  
Vol 690 ◽  
pp. 286-289 ◽  
Author(s):  
Kristina Schlüter ◽  
Julia Reverey ◽  
Norbert Hort ◽  
Christiane Zamponi ◽  
Eckhard Quandt

Mg based thin films are of increasing interest due to the potential in varying the corrosion properties in comparison to bulk alloys of the same nominal composition. In this work the mechanical behaviour and the corrosion performance of sputtered thin films consisting of magnesium alloys with the compositions Mg4Y3Gd and Mg4Y3Nd were investigated by tensile tests and electrochemical corrosion tests, respectively. The tensile tests showed that the sputtering parameters have an enormous influence on the mechanical properties of the thin films. By variation of the Ar sputtering pressure and the DC sputtering power it was possible to fabricate films with widely varying mechanical behaviour reaching from brittle to very ductile films which could be strained to more than 30%. The determined dependency between mechanical properties and deposition conditions was found to be present in both investigated alloys. The corrosion tests revealed that the corrosion behaviour of the investigated samples is not correlated to the mechanical properties of the thin films, as the rate of corrosion and the tendency to localized corrosion do not change significantly upon the deposition conditions, which dramatically influence the mechanical properties.


2009 ◽  
Vol 42 (6) ◽  
pp. 1073-1084 ◽  
Author(s):  
D. Faurie ◽  
O. Castelnau ◽  
R. Brenner ◽  
P.-O. Renault ◽  
E. Le Bourhis ◽  
...  

In situtensile tests have been carried out under synchrotron radiation on supported gold (Au) thin films exhibiting a pronounced crystallographic texture. The 2θ shift of X-ray diffraction lines has been recorded for different specimen orientations and several loading levels in the elastic domain. The data obtained demonstrate the large strain heterogeneities generated within the specimen because of the intergranular interactions associated with the large elastic anisotropy of Au grains. To interpret these results, the use of a multi-scale micromechanical approach is unavoidable. The theoretical background of such methods is described, and the points where exact results can be obtained and where approximations have to be introduced are highlighted. It is shown that the Vook–Witt model, for which a general formulation is provided, is the exact solution for polycrystals exhibiting a laminate microstructure, which is a significant departure from the standard thin-film microstructures. Among several standard models used in the field, the self-consistent model is the only one that reproduces the experimental data correctly. This is achieved by accounting for the actual crystallographic texture of the specimen, and assuming pancake-shaped two-point statistics for the morphological texture. A discussion of the limitations of this approach, originally developed for bulk materials, is given for the specific case of thin films.


1999 ◽  
Vol 11 (4) ◽  
pp. 258-262
Author(s):  
Seiji Shimizu ◽  
◽  
Katsutoshi Kuribayashi

We studied the transformation and mechanical properties of Ti- 54.8-51.6 at % Ni shape memory alloy thin film actuators sputter-deposited at different argon pressures of 0.47-3.4 Pa. The higher the argon pressure, the lower the nickel composition. TiNi thin films were crystallized at 800C for 10min, aged at 400C for 6h, and analyzed by differential scanning calorimetry and tensile tests. All films showed 2-step transformation of martensite, R, and austenite phases. The maximum generative stress of 365MPa was obtained when the TiNi thin film actuator deposited at 2.0Pa was heated electrically to 30A/mm2 after deformation of 3.0% at room temperature.


Author(s):  
Thomas Pardoen ◽  
Asmahan Safi ◽  
Michae¨l Coulombier ◽  
Pierre Carbonnelle ◽  
Jean-Pierre Raskin ◽  
...  

A novel, versatile concept of micromachines has been developed to measure the mechanical response of films, beams or tubes, with thickness ranging between 10 to 1000 nm. Its capacity to study large strains and fracture is one of its key advantages. This new technique has been used to characterize the elastic modulus and fracture stress of two types of brittle films: polysilicon and silicon nitride. The Young’s modulus agrees with the literature data. The fracture stress of polysilicon is shown to increase with decreasing specimen surface size, in agreement with the recent literature. In addition, uniaxial tensile tests have been performed on 210 nm-thick Al films up to fracture. These results show that large ductility can be obtained in very thin freestanding films, which is important for many micro- and nano-systems developments.


2003 ◽  
Vol 782 ◽  
Author(s):  
Nian Zhang ◽  
Changjin Xie ◽  
Wei Tong

ABSTRACTThe existing interpretations of indentation test data (either theoretical or numerical approaches) have been largely based on isotropic plasticity models of polycrystalline materials while most of the metallic thin films widely used in many microelectronic and MEMS applications are strongly textured with a few grains or only a single grain running through the thickness of the films. The multicrystalline nature of the thin films on correlating their indentation and tensile properties is the focus of our investigation. Using multicrystalline aluminum and copper alloy thin sheets as model material systems, both tensile tests and indentation tests were performed and the testing results were compared based on a 3D crystal plasticity finite element analysis. The correlation between the indentation data and the tensile test data (at an effective or equivalent strain) is critically examined for these two multicrystalline materials.


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