Engineering Commons^™

In Situ High Temperature Tem Tensile Testing Of Pseudo Single Crystalline Si For Photovoltaic Applications, Arthur Lantreibecq, Etienne Pihan, Jean Francois Monchoux, Marc Legros

Nanomechanical Testing in Materials Research and Development V

Single crystalline Silicon has the highest efficiency to convert sunlight into electricity. Its production is however costly. On the other hand, cheap polycrystalline Si cells can be produced, with a 10% lower PV conversion efficiency. A promising technique, dubbed "mono-like" Si consists in growing pseudo-single crystalline Si ingots from a tile of single crystalline seeds aligned at the bottom of the crucible. At the present time, this technique is confronted to the high density of defects that multiply during solidification, fueled by the thermal gradients generated in the furnace. Some of these defects have small impact on the electrical properties …

High-Temperature Nano-Impact Testing Of A Hard-Coating System, James Best, Gaylord Guillonneau, Serge Grop, Damian Frey, Quentin Longchamp, Jean-Marc Breguet

Nanomechanical Testing in Materials Research and Development V

Forging and cutting tools for high-temperature applications are often protected using hard nanostructured ceramic coatings. While a moderate amount of knowledge exists for material properties at room temperatures, significantly less is known about the system constituents at the elevated temperatures generated during service. For rational engineering design of such systems, it is therefore important to have methodologies for testing these materials to understand their properties under such conditions (i.e. high strain rate, temperature, or impact).

In this work, we present our first results using a newly developed Alemnis piezo actuated nanoindenter device which utilizes dynamic indentation testing at frequencies approaching …

Numerical Simulations Of Twin Formation And Extension In Thin Face-Centred Cubic Metallic Films, Romuald Bejaud, Sandrine Brochard, Julien Durick

Nanomechanical Testing in Materials Research and Development V

The basic mechanisms of plasticity in face-centred cubic materials are now well known in bulk materials. However, several experimental studies have shown that at the nanoscale, some of its mechanisms can induce surprising mechanical properties when compared to bulk behaviour. The formation and extension of twins in metallic nanowire can, for example, generate super-plasticity [1] or the presence of growth nano-twins within a material can lead to strengthening effects [2]. Atomic simulations are particularly adapted for studying the plasticity mechanisms at play, since they allow their visualization at the atomic scale.

While many atomistic simulations studies have been focused on …

Environmentally Controlled Modulus Mapping Of Biocomposite Materials Employing The Concept Of Effective Mass, Bernd Bayerlein, Igor Zlotnikov

Nanomechanical Testing in Materials Research and Development V

Living organisms are known to form a large variety of mineral-organic composite structures with mechanical properties that combine high stiffness, strength, toughness and perform at different levels of relative humidity (RH). Usually, the organic components are spatially limited to sub-micrometer features and are confined by a much stiffer mineral material. Mechanical characterization of these organic features, whose properties are strongly influenced by RH, presents a real technical challenge. In the present work we demonstrate our ability to measure environmentally dependent static and dynamic mechanical performance of 1 µm thick organic films in the prismatic layer of the mollusc shell Pinna …

Elevated Temperature Microcompression Transient Testing Of Nanocrystalline Materials: Creep, Stress Relaxation And Strain Rate Jump Tests, Gaurav Mohanty, Juri Wehrs, Madoka Hasegawa, Laetitia Philippe, Jeffrey Wheeler, Brad Boyce, Johan Michler

Nanomechanical Testing in Materials Research and Development V

Traditionally, time-dependent properties of nanocrystalline metals have been measured on bulk samples. With the advent of thin film deposition techniques like sputtering and electrodeposition for fabricating nanocrystalline materials, it has become necessary to adapt bulk mechanical testing for thin films. Nanoindentation has been extensively applied for this purpose, particularly on thin films where conventional testing is difficult or impossible, and has been demonstrated to successfully extract strain rate exponents [1]. However, the interpretation of the indentation results can be difficult due to the complex stress state, and the nearly instantaneous onset of large-strain plasticity. Microcompression, on the other …

Deformation And Fatigue Behavior Measurement Of Thin Films Undergoing Thermomechanical Loading At High Strain Rates – A Novel Test Setup, Tariqul Islam, Johannes Zechner, Mirko Bernardoni, Michael Nelhiebel, Reinhard Pippan

Nanomechanical Testing in Materials Research and Development V

The deformation and fatigue behavior of thin films on substrates undergoing either single or repetitive thermo-mechanical loading has been investigated extensively in the last years due to the high relevance for industrial applications, ranging from cutting tools to microelectronic devices.

A popular method to evaluate the stresses occurring in the thin film during temperature cycling is to measure the change in the curvature of the thin film on the substrate during heating and cooling. From the change in curvature, knowing the elastic constants of the substrate and the film and substrate thickness, the stresses in the film can be calculated …

Characterization Of Mechanical Behavior Of Nanocrystalline Layer Induced By Smat Using Micro-Pillar Compression Technique Coupled With Finite Element Analysis, Delphine Retraint, Zhidan Sun, Yangcan Wu, Bruno Guelorget, Laurent Waltz

Nanomechanical Testing in Materials Research and Development V

Micro-pillar compression tests were used to study the mechanical behavior of a stainless steel that has undergone SMAT (Surface Mechanical Attrition Treatment). Micro-pillars were machined using a Focused Ion Beam (FIB) on the cross-section of a SMATed specimen at different distances from the treated surface. These micro-pillars were thus located in different areas more or less affected by the SMAT. They were then compressed with a flat head mounted on a nanoindenter to obtain loading-displacement curves. These compression tests can give information on the mechanical gradient present from the top surface down to the bulk material after SMAT: a superficial …

Micromechanical Testing Of Ion-Irradiated Ferritic/Martensitic Steels, Anna Kareer, Steve Roberts, Peter Hosemann, Gary Was

Nanomechanical Testing in Materials Research and Development V

Ferritic/martensitic steels are the leading candidate material for structural components in the design of Gen IV reactors. They are known to exhibit high mechanical strength, ductility and toughness in the unirradiated condition and show good irradiation resistance with respect to void swelling, irradiation creep, irradiation-induced phase instabilities and high temperature helium embrittlement. Determining the mechanical properties of these structural materials after exposure to irradiation damage is essential for the safe design of the reactors. Testing neutron irradiated, bulk specimens is expensive and requires the use of a hot-cell, however, self-ion irradiation can been used as a proxy to emulate the …

Interface Fracture Resistance Of Thin Films At Elevated Temperatures, Rafel Soler, Sriam Venkatesan, Roman Roth, Johannes Zechner, Michael Nelhiebel, Josef Fugger, Christoph Kirchlechner, Gerhard Dehm

Nanomechanical Testing in Materials Research and Development V

Reliability of modern microelectronic devices is strongly influenced by the delamination resistance of the many bimaterial interfaces present on the device. In particular, metal-ceramic systems are of increasing interest in microelectronic applications because the metallization layer also act as a diffusion barrier. However, these systems can suffer from weak interfaces, leading to catastrophic delamination failures during device operation. Interface failure in such complex multi-layered structures is usually driven by thermal expansion mismatch stresses, both produced during the thin film growth process (and subsequent cooling from processing temperatures) and from thermal cycling during device operation. It is well known that structural …

Final Program, Engineering Conferences International

Nanomechanical Testing in Materials Research and Development V

No abstract provided.

A Universal Characterization Method On Viscous Materials Using Depth Sensing Indentation, Abdul Shah, Nathalie Renevier, Ian Sherrington

Nanomechanical Testing in Materials Research and Development V

Miniaturisation of devices and a paradigm shift toward using compliant material require small scale characterisation techniques such as nanoindentation [1]. Initial non-conformity of contact and delayed elasticity on the unloading curve are not currently taking into account in nanoindentation methods [2, 3], where the unloading curve is seen fully elastic. A different approach has been taken which considers actual localised deformation during nanoindentation, thus the proposed method [4] is able to acquire untainted elastic or viscoelastic response data. The method, validated for both viscous and non-viscous materials, takes into account the correction of the stiffness associated with the delayed elasticity …

A New Designed 1200 °C High Temperature Instrumented Nano Indentation Probe To Investigate The Mechanical Behavior Of Materials, Bruno Passily, Michel Fajfrowaski

Nanomechanical Testing in Materials Research and Development V

The integrity of thermal barrier coating systems is strongly influenced by the mechanical properties of the different layers constituting them, in particular the metallic bondcoat (NiAl-based or MCrAlY alloy). At high temperature, interdiffusion and oxidation phenomena cause changes in the composition of the bondcoats and as a result their mechanical behaviour is likely to change also.

To determine the mechanical behaviour of such alloys in particular, Onera initially designed and developed a high temperature instrumented microindenter capable of functioning up to 1000°C. In a second time, Michalex has developed his own instrumented nanoindenter using Onera know-how.

Several technological solutions have …

Fracture Strength Testing At The Micron-Scale On An Ultra-Fine Grained Wcr10- Ti2 Alloy, Moritz Lessman, Paul Mummery, Chis Hardie, Michael Porton, Carmen Garcia-Rosales, Aida Calvo, Milko Jaksic

Nanomechanical Testing in Materials Research and Development V

The fracture strength of a W-Cr10-Ti2 alloy, manufactured through mechanical alloying and subsequent hot isostatic pressing, has been measured through means of micro-cantilever testing at the Culham Materials Research Facility. The material is a product of ongoing work into self-passivating Tungsten alloys at CEIT, Spain [1] and was chosen for this work due to its fine micro-structure (average grain size

Heavy ion implantations to a depth of 3.5µm and an average damage of 0.7 and 7dpa were conducted at RBI, Zagreb in order to assess the effects of nuclear fusion relevant irradiation damage on the fracture strength of the material. …

Size-Dependent Mechanical Properties Of Crystalline Nanoparticles, Dan | Mordehai

Nanomechanical Testing in Materials Research and Development V

Defect-free crystalline nanostructures reach strengths which are close to their ultimate shear strength, since their deformation is controlled by dislocation nucleation from the surfaces. In this talk we examine how the size and shape of defect-free nanoparticles affect their mechanical properties. In the first part we discuss the indentation response. Earlier experiments on Au nanoparticles showed that they become easier to indent as they are smaller [1]. With large scale Molecular Dynamics Simulations, we show how the lateral dimensions give rise to size effect in indentation through the competition between dislocation storage and depletion on free surfaces. The latter mechanism …

Microscopic Three-Point Bending Test To Probe Plate-Like Silicon Particles From Alsi Alloys, Martin Mueller, Goran Zagar, Marta Fornabaio, Andreas Mortensen

Nanomechanical Testing in Materials Research and Development V

The strength of composite materials and alloys is often governed by the intrinsic strength of brittle microscopic particles that they contain. Approaches to measure the strength of alloy or composite reinforcing particles are usually indirect: average microscopic mechanical properties are estimated via a given model from macroscopic mechanical data conducted on the composite or alloy. Here we present an approach to directly measure the local strength of microscopic second-phase particles of high aspect ratio, by means of which one can identify and understand the role of their strength-limiting defects.

The approach is a microscopic three-point bending test conducted directly on …

Pushing The Envelope For High Temperature Nanoindentation Measurements, Marcello Conte, G. Mohanty, J. Schwiedrzik, D. Ciani, D. Bellanton, N.X. Randall, J. Michler

Nanomechanical Testing in Materials Research and Development V

One of the primary motivations for development of instrumented indentation was to measure the mechanical properties of thin films and individual phases/grains. Characterization of thin film mechanical properties as a function of temperature is of immense industrial and scientific interest. The major bottlenecks in elevated temperature measurements have been thermal drift, signal stability (noise) and oxidation of the surfaces. Thermal drift is a measurement artifact that arises due to thermal expansion/contraction of indenter tip and loading column. This gets superimposed on the mechanical behavior data precluding accurate extraction of mechanical properties of the sample at elevated temperatures. Vacuum is essential …

Identification Of In Situ Lignin Strength Based On Micropillar Compression And Micromechanical Modeling Of Wood Cell Walls, Jakob Schwiedrzik, Rejin Raghavan, Markus Ruggerberg, Silla Hansen, Juri Wehrs, Ramesh Adusumalli, Johann Michler, Tanjia Zimmerman

Nanomechanical Testing in Materials Research and Development V

Many biological materials feature a hierarchical architecture with remarkable mechanical properties combining low weight with both toughness and strength. In order to better understand the mechanisms leading to this unusual combination of traits, structure-property relationships have to be assessed on all length scales. Wood is such a hierarchical material. Its cell walls feature semi-crystalline cellulose fibrils embedded in an amorphous polymer network that are aligned at an angle to the cell main axis resembling a fiber reinforced composite.

Continuum micromechanics can predict mechanical behavior on a higher length scale based on the composition, microstructure, and properties of the individual phases. …

Fundamental Nanomechanic Investigations Using Combinatorial Deposition Techniques, Rachel Schoeppner, Aidan Taylor, Jakob Schwiedrzik, Gaurav Mohanty, Vipin Chawala, Lazlo Petho, Keith Thomas, Johannes Zecher, Carlos Guerra-Nuñez, Johann Michler

Nanomechanical Testing in Materials Research and Development V

Combinatorial materials design of thin films allows for the investigation of broad ranges of both thickness and composition within a single sample; this can be utilized both for fundamental nanomechanics investigations and for the optimization of thin films for engineering applications. Using a unique self-constructed deposition chamber that combines magnetron sputtering, e-beam evaporation, nanoparticle deposition and atomic layer deposition (ALD), the architectural design of thin films can be tailored to study multiple physical and chemical properties.

Recent investigations have focused on using this chamber’s unique ability to create a gradient composition film of up to three different materials with a …

Combining Nanoindentation With Complementary Techniques For Mechanical And Structural Characterization Of Ultra Uow-K (Ulk) Thin Films, Andre Clausner, Ehrendried Zschech, Martin Gall, Yvonne Standke, Malgorzata Kopycinska, Kong Boon Yeap, Khashayar Pakbaz, Reinhard Krause-Rehberg, Dieter Schneider

Nanomechanical Testing in Materials Research and Development V

Nano-porous dielectrics used as insulating materials between on-chip interconnects are an important component in metallization stacks of leading-edge microelectronic products to reduce electrical signal delay and power loss. The main drawbacks of these porous dielectrics are their weak mechanical properties. Therefore, new types of porous organosilicate glasses (OSGs) exhibiting a pore arrangement with a high degree of intermittency were developed to improve their mechanical properties. In this study, we will show the relationship between porosity, pore topology, and elastic modulus based on simulations as well as experimental studies using several OSG films. The main part of this study are the …

Layer Orientation And Size Effects On Micropillar Compression Of Al/Sic Nanolaminates, Lingwei Yang, Carl Mayer, Nik Chawla, Javier Llorca, Jon Molina

Nanomechanical Testing in Materials Research and Development V

Nanolaminates consisting of alternating layers of two dissimilar materials can possess extraordinary mechanical properties compared to their bulk counterparts, making them promising for engineering applications. Extremely high room temperature strengths and damage tolerance have been reported when the individual layer thicknesses are less than 100 nm, and this has been attributed to the large density of interfaces and grain boundaries that act as barriers for pinned dislocations [1–3]. Micropillar compression tests have been extensively employed to study nanolaminate deformation with the force generally applied perpendicular to the individual layers [1,4,5]. However, studies covering the effect of pillar size and layer …

Measuring The Strength Of Brittle Microscopic Spheres By Means Of Compression Tests, Vaclav Pejchal, Goran Zagar, Marta Fornabaio, Raphael Charvet, Cyril Denerez, Andreas Mortensen

Nanomechanical Testing in Materials Research and Development V

The strength of particles is an important property relevant to many industries; in materials science, a wide range of composites and alloys contain small particulate phases, whose microscale strength distribution affects strongly the macroscopic properties of the composite or alloy in question. Yet, despite its importance, the strength of microscopic particles has remained difficult to measure. The most common method used to measure the strength of individual particles is the compression test, conducted by squeezing individual particles between two parallel platens. Progress in nano- and micromechanical testing in recent years has enabled to expand the application of this method to …

High Temperature Mechanical Properties Of Ni-Base Superalloy And Diffusion Aluminide Bond Coating: An In-Situ Sem Nanoindentation Study, Sanjit Bhowmick, Douglas Stauffer, Sayed Asif

Nanomechanical Testing in Materials Research and Development V

High-strength structural materials such as Ni-based superalloys and diffusion bond coats are widely used in challenging environments and with exposure to mechanical fatigue, particle impact, and erosion at elevated temperatures. Diffusion aluminide bond coats are an example of compositionally and microstructurally graded coatings with significant variation in engineered mechanical properties across the cross-section. Nanoindentation, particularly in situ, can be considered as a well-suited technique for measuring the properties of such complex microstructural materials as the deformation volume can be carefully controlled to probe different precipitates and microstructural zones. In this study, an SEM nanomechanical instrument, PicoIndenter 87xR, with an integrated …

Fracture Behavior Of Brittle Ceramics At The Nanoscale, Dahye Shin, Yeesun Na, Kisun Kim, Seokwoo Jeon, Dongchan Jang

Nanomechanical Testing in Materials Research and Development V

In spite of the excellent properties such as high hardness, low thermal expansion, enhanced resistance to chemical degradation and superior mechanical behavior at elevated temperature, ceramic materials usually suffer from the brittle fracture and catastrophic failure, which restrict them from being used for structural applications. While a number of researchers have strived to overcome this drawback of ceramic materials by constructing the microstructures that interfere with crack growth, recent theoretical and computational studies proposed another effective method to suppress the rapid crack propagation by reducing the specimen size down to the nanometer scale.

In this study, we investigated the mechanical …

High-Temperature Fracture Test Using Chevron-Notched Tungsten Microcantilevers, Bo-Shiuan Li, David Armstrong, James Marrow, Steve Roberts

Nanomechanical Testing in Materials Research and Development V

The combination of focused-ion beam (FIB) based sample preparation and nanoindentation allows fracture tests to be conducted at the micro-scale. Micro-fracture tests are of great interest to the nuclear materials community, as it allows direct measurements of fracture toughness within thin ion-irradiated layers and significantly reduces the volume of radioactive samples required as compared to working with neutron irradiated samples.

The main drawback of existing micro-fracture tests is its limitation to brittle materials, as only linear-elastic fracture mechanics (LEFM) solutions have been developed so far. Tungsten-tantalum (W-Ta) alloy, is the primary candidate material for the plasma facing components of a …

Mechanical Scaling Behavior Of Nanoporous Gold Based On 3d Structural Analysis And Indentation-Based Testing, Erica Lilleodden, Kaixiong Hu, Markus Ziehmer

Nanomechanical Testing in Materials Research and Development V

The strength of nanoporous gold (npg) has been shown to be strongly dependent on the length-scale of the gold ligaments, an observation consistent with countless micromechanical experiments that show the typical trend of “smaller is stronger”. Such size-dependent strength can be exploited in npg through targeted annealing in order to tailor the structures for specific applications. However, this approach to structural optimization requires adequate scaling laws for the prediction of strength as a function of structural length-scale, an approach reliant on the assumption of self-similarity of the coarsened structure. Here we present evidence from high resolution 3D structural characterization that …

Nanotwin Governed Toughening Mechanism In Hierarchically Structured Materials, Sungwin Moon, Subin Lee, Jiwon Jeong, Minhyug Kwon, Sang Ho Oh, Sheng Yi

Nanomechanical Testing in Materials Research and Development V

As an important class of natural biocomposite materials, mollusk shells possess remarkable mechanical strength and toughness as a consequence of their hierarchical structuring of soft organic and hard mineral constituents through biomineralization. Strombus gigas, one of the toughest mollusk shell (99 wt% CaCO₃, 1 wt% organic), contains high density of nanoscale {110} growth twins in its third order lamellae, the basic building block of the material [1]. Although the existence of these nanotwins has been known for decades their roles and functions in mechanical behaviors and properties of biological materials are still unrevealed because numerous studies in recent …

Free Energy Function Of Dislocation Densities By Large Scale Atomistic Simulations, Cristoph Begau, Godehard Sutmann, Alexander Hartmaier

Nanomechanical Testing in Materials Research and Development V

The energy of complex dislocation microstructures is a fundamental property of continuum plasticity on the nanoscale. The question how the energy depends on the characteristic of a dislocation network is still not fully answered, although various - and often contradicting - models have been proposed in the literature.

In this talk, this question is addressed using large scale Molecular Dynamics simulations of nanoindentation, which have been conducted to gain insight into the relationship between dislocation microstructures and the associated free energy from an atomistic level. Several single crystalline samples of aluminum are indented using varying tip radii to study possible …

Orientation-Depedent Mechanical Behaviour Of Electrodeposited Copper With Nanoscale Twins, Maxime Mieszala, Guillonneau Gayrlord, Jeffrey Wheeler, Rejin Raghavan, Madoka Hasegawa, Johann Michler, Laetitia Phillippe

Nanomechanical Testing in Materials Research and Development V

The electrodeposition of copper is an important technology for the fabrication of micro-components and interconnects. In contrast to nanocrystalline copper, nanotwinned Cu (nt-Cu) exhibits remarkable strength, ductility and electrical conductivity¹. Our recent work² reported the possibility to deposit copper samples with highly-oriented nanoscale twins by pulse electrodeposition. The twin orientation was altered from horizontal to vertical by changing the applied potential and the twin spacing was controlled with pulse-off time.

In this poster, we report the orientation-dependent mechanical properties of electrodeposited copper with nanoscale twins confined within micron-sized columnar grains. The strength and strain rate sensitivity are …

Grain Size Strengthening – Just Another Length-Scale Effect?, Andy Bushby, David Dunstan

Nanomechanical Testing in Materials Research and Development V

The grain-size dependence of the strength of polycrystalline metals has been described by the Hall-Petch relation (equation 1) since 1951, where the yield or flow stress, s, is related to the inverse square root of grain size, d, and the Hall-Petch constant k_HP.

We have surveyed many of the classical data sets in the literature and find that, in fact, very few support this relationship [1]. Figure 1 shows that values of k_HP are a function of the inverse square root of the grain size rather than being an independent constant, implying that both the constant …

A Comprehensive Study On The Deformation Behavior Of Ultra-Fine Grained And Ultra-Fine Porous Au At Elevated Temperatures, Alexander Leitner, Verena Maier, Erich Schmid, Peter Hosemann, Daniel Kiener

Nanomechanical Testing in Materials Research and Development V

Modern design and engineering of highly efficient devices and machines demand innovative materials to satisfy requirements such as high strength at low density. The purpose of this study was to compare mechanical properties and deformation behavior of ultra-fine grained Au and its ultra-fine porous counterpart, both fabricated from the same base material. Microstructural investigations of the foam surrendered a ligament size of approximately 100 nm consisting of ~60 nm grains in average. The ultra-fine grained Au features a mean grain size of 250 nm.

Nanoindentation is a convenient technique to obtain materials properties at ambient but also at non-ambient conditions …