Materials Science and Engineering Commons^™

Length-Scale Dependent Deformation Behavior Of Nanolayered Cu-Based Micropillars, Gang Liu, Jin Zhang, Jun Sun

Nanomechanical Testing in Materials Research and Development V

By using microcompression methodology, deformation of nanolayered crystal/crystal (C/C) Cu/Zr and Cu/ Cr, and crystal/amorphous (C/A) Cu/CuZr micropillars was systematically investigated within wide ranges of intrinsic layer thickness (5 – 150 nm) and extrinsic sample diameter (300 – 1500 nm). The intrinsic size effect, extrinsic size effect and their interplay were respectively revealed. Competition between the intrinsic and extrinsic size effects leads to a common experimental observation of a critical layer thickness of about 20 nm, above which the deformation is predominantly intrinsic-size-related and insensitive to sample size, while below which the two size effects are comparable. The underlying deformation …

How Residual Stresses Affect The Fracture Properties Of Layered Thin Films, D. Kiener, R. Treml, D. Kozic, J. Keckes, J. Zechner

Nanomechanical Testing in Materials Research and Development V

The continued miniaturization effort has revealed exciting new material behavior at small length scales, where pronounced size effects come into play and material properties are subject to change. This has led to the development of miniaturized testing techniques to determine local plastic properties. So far, however, only few efforts regarding the determination of residual stresses and fracture properties in miniaturized systems were made.

In this presentation, we will focus on recent developments regarding the measurement of residual stresses and miniaturized fracture properties using FIB based sample preparation and in situ SEM experiments. The depth resolved residual film stresses are determined …

In-Situ Nano-Mechanical Tests In The Light Of Μlaue Diffraction, Thomas Cornelius, Cedric Leclere, Zhe Ren, Anton Davydok, Olivier Thomas

Nanomechanical Testing in Materials Research and Development V

In the recent past, low-dimensional materials attracted enormous attention due to the extraordinary properties found for nanostructures compared to their bulk counterparts. For instance, micro- and nano-mechanical tests revealed an increasing yield strength with decreasing size of the structure reaching the ultimate limit of the material for nanowires. While bulk fcc metals fail at stresses of few MPa, ultra-high strengths were demonstrated for gold nanowires with an elastic limit of few GPa [1, 2]. Additionally, while semiconductors such as Si and InSb are brittle at room temperature and become ductile at elevated temperatures of few hundred degrees Celsius, pillars of …

Nano-Scale Behavior Of Irradiated Nano-Structured Alloys, David Armstrong, John Waite, Steve Fitzgerald, Angus Wilkinson, Alan Xu, T. Ben Britton

Nanomechanical Testing in Materials Research and Development V

Future fast neutron fusion and fission nuclear systems will be subjected to levels of radiation damage from fast neutrons which is significantly higher than the current generation of nuclear power stations. This will require innovative materials solutions to allow long term mechanical stability of reactors. One proposed class of materials are nanostructured alloys where the large number of interfaces allow for recombination defects and reduce the degree of radiation hardening seen. However their response under irradiation has not thoroughly been studied. In this work, two irradiated nanostructured alloys have been studied W-5%Re in both a nanostructured and annealed variant and …

Underpinning And Benchmarking Multi-Scale Models With Micro- And Nanoscale Experiments, Kevin Hemker, Zafir Alam, Suman Dasupta, David Eastman, Madhav Reddy, Paul Rottman

Nanomechanical Testing in Materials Research and Development V

Predictive models of materials behavior depend on: accurate databases of constitutive material properties, identification of underlying deformation mechanisms, and the availability of experimentally measured benchmarks with which to compare. Micro- and nano-scale experiments can be used to facilitate collection of salient mechanical properties of individual phases at appropriate temperatures, chemistries and microstructural states. Coupling with TEM observations allows one to identify underlying deformation mechanisms and to imbibe models with the requisite fundamental physics and materials science. Simulations must be benchmarked with experiments, conducted at scale with relevant material volumes and identifiable microstructures. This presentation will outline efforts to characterize the …

Anisotropy Of Ultrafine-Lamellar And Nanolamellar Pearlitic Structures Revealed By In-Situ Micro Compression Testing, Marlene Kapp, Anton Hohenwarter, Stefan Wurster, Bo Yang, Reinhard Pippan

Nanomechanical Testing in Materials Research and Development V

Applying severe plastic deformation to pearlitic steels leads to a transformation of the random ultrafine-lamellar (ufl) colony structure to a nanolamellar (nl) composite. The distinct reduction of the interlamellar spacing generates a high-strength steel with a strength of up to 3.7 GPa, which can readily be produced. Additionally, the ferrite and cementite lamellae align in a preferential direction giving rise to an anisotropic mechanical response.

The aim of this work is to determine the material anisotropy in terms of flow stress and deformation behavior in the nl state and to compare it with its ufl state. Thus, micron sized samples …

In-Situ Mechanical Testing At The Synchrotron, Steven Van Petegem

Nanomechanical Testing in Materials Research and Development V

A major challenge in metallurgy is to understand the relation between the microstructure of a metal and its behaviour under an applied load or temperature. This requires a detailed characterization of the evolution of the microstructure at different length scales through the determination of the crystal structure, defect density, grain size distribution, texture etc.

During last decade in-situ mechanical testing under synchrotron radiation has become a widespread tool to investigate the evolution of the microstructure of single and polycrystals during deformation [1]. Many such in-situ deformation tests are performed during continuous or interrupted uniaxial tensile and/or compression tests. Several microstructural …

Transition In Plastic Deformation Of Nanolayered Thin Films: Role Of Interfaces And Temperature, R. Raghavan, J.M. Wheeler, J. Michler, G. Dehm

Nanomechanical Testing in Materials Research and Development V

Insights into the parameters governing the plasticity of immiscible, nanocrystalline metals stacked in the form of layers are pivotal both from scientific and applications’ perspectives. An outstanding case consists of the contact metallurgy of pure copper used ubiquitously as metallic interconnects in electronic devices. Diffusion barrier layers such W or TiN are necessary to prevent undesirable diffusion of Cu into the Si-based device during synthesis and service. Also, supersaturated Cu-Cr alloys are desirable for improving the strength, while retaining optimal functional properties required for the application. The scientific curiosity lies in understanding the effects of reducing microstructural length scales on …

Hydrogen Effects On Nanoindentation Behavior Of Metallic Glass Ribbons, Yakai Zhao, In-Chul Choi, Moo-Young Seok, Jin-Yoo Suh, Jae-Il Jang

Nanomechanical Testing in Materials Research and Development V

Recently, metallic glass (MG) membranes that are permeable to hydrogen have gained interest due to the increasing importance of hydrogen separation in a number of applications, e.g., hydrogen-powered fuel cells. An important issue in the context of MG membranes is the hydrogen-induced embrittlement and efforts to understand the role played by hydrogen in the mechanical properties, especially yielding and plastic deformation behavior, of MGs are being made. In this study, therefore, an attempt was made by performing nanoindentation tests with cube-corner and spherical indenter tips on a series of Ni–Nb–Zr amorphous alloy ribbons to investigate the hydrogen effects on nanohardness …

Probing Nanoscale Damage Gradients In Irradiated Materials With Spherical Nanoindentation, Nathan Mara, Siddhartha Pathak, Yongqiang Wang, Russ Doerner, Surya Kalidindi

Nanomechanical Testing in Materials Research and Development V

We discuss applications of spherical nanoindentation stress-strain curves in characterizing the local mechanical behavior of materials with modified surfaces. Using ion-irradiation on tungsten as a specific example, we show that a simple variation of the indenter size (radius) can identify the depth of the radiation-induced-damage zone, as well as quantify the behavior of the damaged zone itself. Using corresponding local structure information from electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) we look at (a) the elastic response, elasto-plastic transition, and onset of plasticity in ion-irradiated tungsten under indentation, and compare their relative mechanical behavior to the unirradiated state, …

In-Situ Strain Softening And Strain Hardening Of Natural Geomaterials On The Microscale, Younane Abousleiman, Katherine Hull, Ghaithan Al-Muntasheri, Peter Hosemann, Scott Parker, Cameron Howard

Nanomechanical Testing in Materials Research and Development V

Gas shale has proven to be a good candidate for mechanical characterization using nanoindentation. However, this natural material composed of nano-granular clay and microscale non-clay minerals also includes within its matrix a polymeric material. This kerogen biopolymer is interbedded and intertwined with the clay and non-clay minerals at almost all scales. Figure 1(a) demonstrates the nature of interlacing that occurs between shale rock and organic matter.

Kerogen within the shale matrix has been mechanically characterized using nanoindentation to determine Young’s modulus and hardness such as in the work by Zeszotarski et al. 2004. As a polymer kerogen not only has …

Probing The Initial Stages Of Plasticity With Nanoindentation, Easo George

Nanomechanical Testing in Materials Research and Development V

The probed volumes in nanoindentation can be comparable to the characteristic length scales of some of the defect configurations that control early-stage plastic deformation in metals. Representative examples from work carried out with my collaborators will be reviewed with a view to shedding light on the elementary processes associated with the transition from elastic to plastic deformation. Among the topics to be discussed are: homogeneous versus heterogeneous dislocation nucleation, nucleation versus activation of pre-existing dislocations, effects of source density, pinning by interstitial elements, and influence of crystal structure.

Nanoindentation-Based Mechanical Spectroscopy Of Wood Cell Walls, Joseph Jakes

Nanomechanical Testing in Materials Research and Development V

Mechanical spectroscopy is the assessment of a mechanical index, such as the viscoelastic Young’s modulus or the plastic flow stress, across a broad spectrum of time scale, deformation rate, temperature, or moisture content. In addition to providing thorough mechanical characterization, which is useful to predict material performance over a wide range of conditions, mechanical spectroscopy also provides information about the microphysical processes which are causally linked to the properties. Recently, broadband nanoindentation creep (BNC) has been developed to measure viscoplastic properties across 4-6 decades of strain rate and broadband nanoindentation viscoelasticity (BNV) to measure viscoelastic properties across greater than 4 …

In-Situ Micropillar Compression Of Bone Shows Remarkable Strength And Ductility But No Damage, Jakob Schwiedrzik, Rejin Raghavan, Alexander Burki, Uwe Wolfram, Phillippe Zysset, Johann Michler

Nanomechanical Testing in Materials Research and Development V

Bone is a hierarchical composite material featuring a cell-seeded mineralized collagen matrix. It is designed for mechanical support, metabolizing minerals and storing bone marrow. Its strength depends on the amount of mineral measured by clinical densitometry, but also on the micromechanical properties of the bone hierarchical organization. A good understanding has been reached for elastic properties on several length scales, but up to now there is a lack of data with respect to plasticity at the lower length scales. An experimental setup for micromechanical testing allowing a straightforward interpretation of the data due to the uniaxial stress state is micropillar …

Performance Of A Single Interface In A Biocomposite Structure Measured Using Microcantilever Modulation Experiment, Igor Zlotnikov, Bernd Bayerlein, Benny Bar-On

Nanomechanical Testing in Materials Research and Development V

Biological mineral-organic composite materials are known to be tough, stiff, stable, viscoelastic bodies capable to creep, recover, absorb energy and even filter particular vibrations. This exceptional mechanical functionality is associated with intricate hierarchical architectures of biocomposites which often consist of stiff mineral units surrounded by extremely thin organic interfaces. The latter play a critical but poorly understood role in the unique static and dynamic performance of the bulk. In this work we propose a new method to study static and dynamic mechanical performance of a single thin interface in a biocomposite structure which is based on force modulation experiment (performed …

Importance Of Dynamics In Small Scale Mechanical Testing: Fast Constant Strain Rate And Ballistic Testing, Sudharstan Phani, Warren Oliver

Nanomechanical Testing in Materials Research and Development V

Recent advances in electronics have enabled nanomechanical measurements with very low noise levels at fast time constants and high data acquisition rates. Nanomechanical testers with sub-nanometer noise levels at a displacement time constant of 20µs are currently available which open the doors for a wide range of ultra-fast nanomechanical testing. It not only enables accurate measurement of materials’ response during a dynamic event such as strain burst (pop-in) during micropillar or indentation testing, but also enables fast indentation tests. However, fast testing requires a precise understanding of the instrument’s dynamic response along with the time constants of the measurement signals. …

Effect Of Hydriding On Nanoscale Plasticity Mechanisms In Nanocrystalline Palladium Thin Films, Behnam Amin Ahmadi, Hosni Idrissi, Marc Fivel, Ranaud Delmelle, Stuart Turner, Thomas Pardoen, Joris Proost, Dominique Schryvers

Nanomechanical Testing in Materials Research and Development V

Thin palladium (Pd) membranes constitute an enabling material in hydrogen permeation and sensing applications. During hydriding of Pd, as long as the H/Pd (atomic ratio) stays below α_SSmax≈0.02, the α-Pd with face centered cubic (fcc) lattice will expand from 3.889 Å to 3.895 Å. When the ratio reaches 0.02 a β-phase, again fcc based, having a lattice constant near 4.025 Å appears which induces a 10% volume change. In the present work, nanoscale plasticity mechanisms activated in sputtered nanocrystalline (nc) Pd thin films subjected to hydriding at different hydrogen pressures have been investigated for the first time using …

Effect Of Hydrogen On The Nucleation And Motion Of Dislocations, Mohammad Zamanzade, Jorge Velayarce, Christian Motz, Oscar Torrents Abad, Afrooz Barnoush

Nanomechanical Testing in Materials Research and Development V

Conventional mechanical tests are costly, time consuming, and due to their large scale, not very successful in obtaining mechanistic information. In contrast, the local method like nanoindentation, compression or bending test of micro pillars have comprehensive ranges of possibilities to achieve an essential understanding about the influence of substitutional atoms and/or interstitial atoms (e.g., hydrogen and nitrogen) on the mechanical properties like Young´s modulus, Gibbs free energy for homogeneous dislocation nucleation, dislocation line energy and also friction stress. These methods allow us to measure the mechanical behavior in simulated environments and atmospheres close to the routine industrial applications.

Nanoindentation was …

How To Perform Nanoindentation In Difficult Conditions? Applications To Ultra Soft Materials And Temperature Environment, Michel Fajfrowski, Vincent Jardret

Nanomechanical Testing in Materials Research and Development V

Measuring ultra soft materials or materials in extreme temperature conditions lead to the same challenges. Both present difficulties related to visco elastic properties. It’s well known that in a dynamic regime, mechanical properties of such materials depend of the strain rate, excitation frequency and temperature. By using a transducer which is not adapted to specific criteria such as a low contact stiffness or ultimate stable thermal conditions, it’s very easy to neglect fundamental testing conditions which can generate significant inaccurate mechanical properties. This transducer does not rely only on the quality of his components and his design. The integration of …

In-Situ Observation Of The Onset Of Plastic Deformation By Prismatic Loop Emission, Sang Ho Oh

Nanomechanical Testing in Materials Research and Development V

We report direct observations on the incipient plasticity of dislocation-free single crystal Au [110] nanowires by in situ transmission electron microscopy nanomechanical testing. The diameter of the tested nanowires ranged from ~ 80 nm to 350 nm and the length-to-diameter ratio was larger than 5. The top end of all [110]-oriented Au nanowires is bound by two inclined {111} faces in a wedge shape, on the other hand the side faces consist of four large {111} and two small {100} planes, resulting in a truncated rhombic cross-section. In our deformation setup where the wedge-shaped growth end of nanowire was compressed …