Structure and mechanical behavior relationship in nano-scaled multilayered materials (original) (raw)
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Hardness, ductility, and thermal processing of Cu/Zr and Cu/Cu_Zr nanoscale multilayer foils
Acta Materialia, 1997
The hardness, ductility, and thermal processing of Cu/Zr and Cu/Cu-Zr multilayers were investigated by indenting, bending, and heating a series of free-standing multilayer foils. The foils were deposited with alternate, nanoscaie layers of Cu and Zr, and then thermally processed to produce three additional nanostructures: alternate layers of Cu and amorphous Cu-Zr(aCu-Zr); alternate layers of Cu and CusiZr14; and a non-layered structure with small Cu grains in large CuqZr? grains. The hardness and ductility of the foils depended strongly on the degree of thermal processing and varied dramatically with the volume fraction of the Zr or Cu-Zr phases in each of the four nanostructures. The dependence of hardness on volume fraction was stronger when the films were indented parallel to their layering than when the foils were indented perpendicular to their layering. This result demonstrates that plastic deformation is anisotropic in these multilayer samples.
2010 27th International Conference on Microelectronics Proceedings, 2010
Multilayered composite systems of alternately electrodeposited nanocrystalline Cu and Ni films on cold-rolled microcrystalline copper substrates were fabricated. Highlydensified parallel interfaces which can give rise to high strength of composites are obtained by depositing layers at a very narrow spacing. The mechanical properties of the composite systems were characterized using Vickers microhardness testing with loads ranging from 1.96 N down to 0.049 N. Dependence of microhardness on layer thickness, Ni/Cu layer thickness ratio and total thickness of the film was investigated. The microhardness increased with decreasing the layer thickness down to 30 nm and it is consistent with the Hall-Petch relation. Composite hardness model of Korsunsky was applied to the experimental data in order to determine the composite film hardness. The highest value of all the composite film hardness values was obtained when the ratio of Ni : Cu layer thickness was 4:1.
Materials Science Engineering a Structural Materials Properties Microstructure and Processing, 2007
The effects of Ni foil thickness on the microstructure and tensile properties of reaction synthesized multilayer composites have been systematically investigated. Multilayer composites have been fabricated by reaction annealing of their foil laminates consisting of 10 m thick Al foils and 20, 50 and 80 m thick Ni foils. Ni 3 Al multilayer composites prepared from 20 m Ni foils were very brittle. Ni/Ni 3 Al multilayer composites prepared from 50 m Ni foils exhibited significant work-hardening and behaved more like a ductile alloy, rather than a composite, with an ultimate tensile strength of 1050 MPa and elongations of >18%. The composites fabricated from 80 m Ni foils, which contain Ni 3 Al precipitates, had a low yield strength and ultimate tensile strength (about 160 and 470 MPa, respectively), and had a very good capacity for plastic deformation (>34% elongation). The dislocations in Ni and Ni 3 Al layers can slide through the Ni 3 Al/Ni interfaces, with the result that the Ni and the Ni 3 Al layers in the composites can cooperatively deform during tensile testing. Delaminated interfaces containing Al 2 O 3 inclusions further promote the capability of the Ni 3 Al layers for plastic deformation. As a result, the Ni/Ni 3 Al multilayer composites exhibit good tensile strengths and a high ductility. The existence of Ni 3 Al precipitates in the Ni layers inhibits cross-slip of dislocations, which results in dislocation networks in the Ni layers which have a preferred orientation.
Size effects on the Mechanical Behavior of Nanometric W/Cu Multilayers
MRS Proceedings, 2008
Le comportement mécanique de multicouches W/Cu nano structurées préparées par pulvérisation ionique a été analysé en utilisant une méthode combinant la diffraction des rayons X et la déformation in situ. Les essais on été réalisés sur une source de lumière synchrotron pour analyser la réponse élastique du tungstène. Trois différentes microstructures on été analysées : l'échantillon composé de la couche de tungstène la plus fine présente un comportement mécanique différent de celui attendu pour un matériau massif. Néanmoins, des mesures par microscopie électronique en transmission (MET) et par diffusion centrale en incidence rasante (GISAXS en anglais) révèlent des discontinuités dans les sous-couches de cuivre. Comme les déformations de ces clusters de cuivre et les contributions des joints de grain ne sont pas expérimentalement accessibles, une approche par simulation atomistique devient indispensable.
Characterization of the surface topography and nano-hardness of Cu/Ni multilayer structures
Central European Journal of Physics, 2011
This article describes the results of a study of Cu/Ni multilayer coatings applied on a monocrystalline Si(100) silicon substrate by the deposition magnetron sputtering technique. Composed of 100 bilayers each, the multilayers were differentiated by the Ni sublayer thickness (1.2 to 3 nm), while maintaining the constant Cu sublayer thickness (2 nm). The multilayer coatings were characterized by assessing their surface topography using atomic force microscopy and their mechanical properties with nano-hardness measurements by the Berkovich method. The tests showed that the hardness of multilayers was substantially influenced by the thickness ratio of Cu and Ni sublayers and by surface roughness. The highest hardness and, at the same time, the lowest roughness was exhibited by a multilayer structure with a Cu-to-Ni sublayer thickness ratio of 2:1.5.
Materials Letters, 2015
Mechanical properties of intermetallic compounds (IMCs) which were formed in electrodeposited Cu/Sn and Cu/Ni/Sn multilayered thin film have been investigated. The layers of Cu, Sn and Ni were formed by electrodeposition technique using copper pyrophosphate, tin methanesulfonic and nickel Watts baths, respectively. After synthesis, samples were subjected to high temperature aging at 150 °C for 168 h. Two different types of intermetallics Cu3Sn and Cu6Sn5 were formed in Cu/Sn. After adding ultra thin layer of Ni (70 nm) in between Cu and Sn layers, (Cu, Ni)6Sn5 was formed after aging at similar condition to that of Cu/Sn. Tin whisker growth was not observed in both samples after preserving the samples in air for 365 days. Hardness and elastic moduli of all three different types of IMCs were measured by using a Hysitron Triboindenter 750 Ubi system. Hardness of the three IMCs Cu3Sn, Cu6Sn5, (Cu, Ni)6Sn5 and Cu were found to be 5.99, 6.61, 7.43 and 1.55 GPa respectively. The addition of Ni suppressed the growth of Cu3Sn greatly. This is expected to lead to better reliability of electronic interconnections as Cu3Sn is often associated with void formation.
Nanocrystalline electrodeposited Ni: microstructure and tensile properties
Acta Mater, 2002
The microstructure of commercially available nanocrystalline (nc) electroplated Ni foils is studied by means of X-ray diffraction and transmission electron microscopy. It is shown that the microstructure is inhomogeneous and batch-dependent. Tensile properties at strain rates between 10−5 and 103 s−1 are studied and compared with the results of coarse-grained Ni. Data on strength, strain-rate sensitivity and work hardening are presented. At the highest strain rates, shear banding with local grain growth is observed in the nc structure. It is also suggested that the differences found in nc Ni for 3 and 20 mm tensile specimens are the size effects related to the inhomogeneous microstructure.
Materials Science and Engineering: A, 2001
The repeated application of mechanical deformation of metallic materials has been proved to be an effective technique for producing bulk nano-scaled regulated structures. These materials have been shown to have unique properties characteristic for nano-materials. This paper reports the experimental results on the mechanical strength, magneto-resistivity, and thermo-electricity obtained by repeated pressing and rolling of alternately stacked thin metallic foils in the Cu-Fe system. In the samples which have the layer thickness greater than 35 nm, the Hall-Petch relation is primarily obeyed. For the samples with the layer thickness less than 35 nm, the strength and hardness deviate from this relation. Large magneto-resistivity change (GMR) have been confirmed and a noted change in thermo-electricity (EMF) dependent on the layer thickness, as observed for the Ag-Fe system, have also been confirmed.
Journal of Applied Physics, 2012
The strain hardening and the related surface pile-up phenomena in CuNi, CuNb and CuNiNb nanoscale multilayered metallic (NMM) composites are investigated using atomistic simulations of nanoindentation on such multilayers with varying individual layer thickness. Using empirical load-stress and displacement-strain relations, the obtained load-depth curves were converted to hardness-strain curves which was then fitted using power law. It is found that the extent of surface pile-up is inversely related to the hardening exponent of the NMMs. Two deformations mechanisms which control the surface pile phenomenon are discovered and discussed. Furthermore, from the stress-strain data, it is found that interfaces and their types play a major role in strain hardening; the strain hardening rate increases with strain when incoherent interfaces are present. The relationship between the hardening parameters and the interfacial dislocation density as well as the relationship between interfacial density and length scales, such as layer thickness and indentation depth, are analyzed, and it is found that the hardness in these NMM has strong inverse power law dependence on the layer thickness. V C 2012 American Institute of Physics. [http://dx.
High-strength sputter-deposited Cu foils with preferred orientation of nanoscale growth twins
2006
Abstract Bulk Cu foils have been synthesized via magnetron sputtering with an average twin spacing of 5 nm. Twin interfaces are of {111} type and normal to the growth direction. Growth twins with such high twin density and preferred orientation have never been observed in elemental metals. These Cu foils exhibited tensile strengths of 1.2 GPa, a factor of 3 higher than that reported earlier for nanocrystalline Cu, average uniform elongation of 1%–2%, and ductile dimple fracture surfaces.