Materials Science and Engineering Commons^™

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 …

In-Situ Nanomechanical Testing Using X-Ray Microscopy, William Harris, Arno Merkle, Benjamin Hornberger, Hrishikesh Bale, Robert Bradley, Xuekun Lu, Philip Withers

Nanomechanical Testing in Materials Research and Development V

Micron-scale X-ray tomography, classically referred to as MicroCT, is a well-established 3D imaging technique and has seen various applications of in situ testing due to flexible sample types, sizes, nondestructive imaging, and lack of need for a vacuum enclosure. Recent advances in lab-based nanoscale X-ray microscopy (XRM) have moved beyond some of the physical constraints of traditional MicroCT by incorporating synchrotron-style optics and detection systems, extending spatial resolution down to 50 nm for samples tens to hundreds of microns in size. These nanoscale X-ray microscopes provide high resolution, nondestructive 3D imaging of interior structures on samples of tens to hundreds …

Size Dependent Deformation Of Beta Brass, Oscar Torrents, Bentejui Medina Clavijo, Carl Frick, Andreas Schneider, Eduard Arzt

Nanomechanical Testing in Materials Research and Development V

Previous research has shown that size scale dictates materials strength, reaching into the GPa range for specimens in the (sub-) micron regime. However, the influence of crystal structure on this ‘size-effect’ is poorly understood. In the present work, the deformation behavior of beta brass, which has a CsCl (B2) crystal structure and a low thermal component to the room temperature strength, has been studied through the compression of focused ion beam manufactured pillars at room temperature. The size dependence of beta brass is found to be close to that observed in FCC metals although the deformation processes differ significantly. While …

Testing Of Nanostructure Within Active Carbons Particles, Bronislaw Buczek

Nanomechanical Testing in Materials Research and Development V

Activation process with water-steam of carbonaceous precursors leading to the production of active carbons is noncatalytic reaction, which takes place in a gas-solid system.

Transport phenomena within porous particles depend strongly on the internal structure of the particles. Not too much experimental work has been done to understand how the tortuosity and hence effective diffusivity within the pore space are affected by the pore size distribution, pore shape, and nanostructure (micro- and mesopores).

The activating gas in the process is thought to penetrate the particle as a result of diffusion accompanied by chemical reactions, the gas concentration decreasing with distance …

A New Technique To Measure The True Contact Area Using Nanoindentation Testing, Gaylord Guillonneau, G. Kermouche, J.M. Bergheau, J.L. Loubet

Nanomechanical Testing in Materials Research and Development V

Nanoindentation technique requires the determination of projected contact area under load for calculation of modulus and hardness of materials. This projected contact area is usually calculated by models which take into account the pile-up or sink-in phenomena around the tip. The most commonly used model was developed by Oliver and Pharr [1] which can precisely model the sink-in around the tip, but cannot account for pile-up. Another model developed by Loubet et al can be used [2]. It can take into account the pile-up and the sink-in phenomena and can precisely measure the projected contact area for a large range …

Thermally Activated Deformation In Cast Aluminium Microwires, Suzanne Verheyden, Jerome Krebs, Andreas Mortensen

Nanomechanical Testing in Materials Research and Development V

We present a study on the thermally activated deformation behavior of aluminium (99.99%) microwires. The wires are prepared through a microcasting process based on a combination of lost pattern casting and pressure infiltration. In this manner microwires with a diameter between 7 and 100 µm can be cast. The wires are monocrystalline, have a surface roughness around 30 nm and are amenable for tensile testing. Their monotonic flow depends strongly on orientation, and displays a large number of stochastically distributed strain bursts. Relaxation tests are conducted on microwires with a diameter between 15 and 100 µm. The relaxations consist of …

Deformation Mechanisms Of Twinned Nanoparticles And Nanowires, Erik Bitzek, Wolfram Nohring, Andreas Kelling, Cynthia Volkert

Nanomechanical Testing in Materials Research and Development V

The plastic deformation of nanoscale metallic specimens has recently attracted a lot of interest due to the reported changes of deformation mechanisms with reduced size. Similarly, the interaction of dislocations with twin boundaries has received lots of attention in the context of the ultrahigh strength and ductility of nanotwinned metals. Here, we present experiments and atomistic simulations of compression test on twinned gold nanoparticles to study dislocation processes and -storage in nanosized volumes and dislocation-twin interaction mechanisms and compare them with the deformation behavior of twinned silver and gold nanowires.

Compression experiments were performed on triangular shaped, facetted particles using …

Length-Scale Enabled Quantification Of Surface Damage By Indentation: A Case Study Separating The Components Of Contact Response Due To Indentation Size, Residual Stress, And Damage Caused By Surface Machining And Grinding, Nigel Jennett, Xiadong Hou

Nanomechanical Testing in Materials Research and Development V

Instrumented indentation is a convenient and increasingly rapid method of high resolution mapping of surface properties. There is, however, significant untapped potential for the quantification of these properties, which is only possible by resolution of a number of serious issues that affect the absolute values for mechanical properties obtained from small indentations. The three most pressing currently are the quantification of the contributions to an indentation result due to: the Indentation Size Effect (ISE); Residual stress; and pile-up and sink-in – which is itself affected by residual stress and ISE.

We take as a case study the mapping of the …

Insights Into Dislocation Grain-Boundary Interaction By X-Ray Μlaue Diffraction, Christoph Kirchlechner, Nataliya Malyar, Peter Imrich, Gerhard Dehm

Nanomechanical Testing in Materials Research and Development V

The deformation behavior of metallic single crystals is size dependent, as shown by several studies during the last decade. Nevertheless, real structures exhibit different interfaces like grain, twin or phase boundaries. Due to the possibly higher stresses at the micron scale, the poor availability of dislocation sources and the importance of diffusion in small dimensions the mechanical behavior of samples containing interfaces can considerable differ from bulk material.

In the talk we show the first in situ µLaue compression experiments on micron sized, bi-crystalline samples. Three different grain-boundary types will be presented and discussed (i) Large Angle grain Boundaries (LAGBs) …

Measuring The Fracture Toughness Of Titanium Carbide Reinforcements At The Micronscale, Lionel Michelet, Martin Mueller, Vaclav Pejchal, Goran Zagar, Andreas Mortensen

Nanomechanical Testing in Materials Research and Development V

It is known that the mechanical properties of composite materials and alloys are strongly influenced by the intrinsic mechanical properties of their reinforcements or second phases. Such local properties are difficult to measure in particulate reinforcements or second phases because of the irregular shape and small size of material samples to be tested. We compare three methods that measure the fracture toughness of TiC reinforcements by combining focused ion beam (FIB) milling methods with nanoindentation techniques and finite element simulation. In-situ created TiC particles in a steel matrix are tested. Such particles are analysed by EBSD to select the crystalline …

A New Dynamic Module For In-Situ Nanomechanical Testing At High Strain Rate, Gaylord Guillonneau, J. Wehrs, G. Mohanty, D. Frey, S. Grop, J. Milchler, J.M. Breguet, Q. Longchamp, J.M. Wheeler

Nanomechanical Testing in Materials Research and Development V

In-situ nanomechanical testing is commonly used to probe surface mechanical properties of bulk materials or thin films, like hardness, Young’s modulus, Yield stress…Actually most of the instruments can measure these properties only statically, i.e. a low frequency, leading to property measurement only at low strain rate (usually 10^-1s^-1 by nanoindentation). This is mainly caused by the low resonance frequency of the system, preventing making tests at higher speed. Performing high dynamic measurements could bring new information on materials properties like deformation mechanism at high strain rate, or high dynamic fatigue properties.

A new high dynamic module usable …

Dislocation Dipoles And The Nucleation Of Cracks In Silicon Nanopillars, J. Rabier, F. Abed El Nabi, J. Godet, S. Brochard, L. Pizzagalli

Nanomechanical Testing in Materials Research and Development V

To understand the brittle to ductile transtion at small scale in silicon nanopillars, plastic deformation of silicon nanopillars was investigated by atomistic simulations. Perfect dislocations were found to be nucleated from surfaces and nano cavities were evidenced resulting from dislocation dipoles annihilation. The formation of such cavities is consistent with previous atomistic calculations showing that the annihilation of dislocation vacancy dipole of perfect shuffle dislocations is associated to the formation of vacancy clusters in silicon and diamond [1]. In nanopillars such cavities contribute to the nucleation of cracks [2]. This mechanism of crack nucleation is relevant to single slip deformation …

Development And Application Of An In-Situ Nanoindenter Coupled With Electrical Measurements, Solene Comby, Fabien Volpi, Florence Robaut, Rachel Martin, Francine Roussel, Frederic Roussel, Didier Pellerin, Marc Verdier

Nanomechanical Testing in Materials Research and Development V

The increasing demand for multifunctionality has become a recurring challenge for a wide panel of application fields such as microelectronics, microsystems, energy harvesting or structural applications.

This generally implies a smart combination of materials with tailored geometries, thus leading to ever more complex structures. The complexity of these new materials requires the development of higher performance characterization tools.

In that purpose, a multifunctional characterization set-up is developed in SIMaP laboratory, mainly based on electrical and mechanical coupling. This set-up is tailored for advanced measurements at the micrometer scale of structural and functional materials displaying small scale microstructure such as multiphase, …