The fracture toughness is a critical material property that determines engineering performance.
However, as is well known for crystalline materials, if certain sample geometry and size
requirements are not met, test results become sample-size dependent and difficult to compare
among different studies. Here, the room-temperature fracture toughness of the Zr-based...
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ActaMaterialia 80 (2014) 507
Erratum
Erratum to
The fracture toughness is a critical material property that determines engineering performance.
However, as is well known for crystalline materials, if certain sample geometry and size
requirements are not met, test results become sample-size dependent and difficult to compare
among different studies. Here, the room-temperature fracture toughness of the Zr-based...
Full Text:
., Ritchie, R. O., & Kruzic, J. J. (2014).
Size-dependent fracture toughness of bulk metallic glasses. Acta
The fracture toughness is a critical material property that determines engineering performance.
However, as is well known for crystalline materials, if certain sample geometry and size
requirements are not met, test results become sample-size dependent and difficult to compare
among different studies. Here, the room-temperature fracture toughness of the Zr-based...
Mechanical property degradation due to the disorder-order phase transformation is of potential concern for alloys based on the Ni-Cr binary system, particularly in nuclear power applications, where component lifetimes can exceed 80 years. In the present research, a disorder-order phase transformation has been studied in the Ni-33 at.% Cr model...
This article presents a novel method combining ion irradiation, in-situ transmission electron microscopy (TEM), and microchemistry analysis before/after irradiation, which allows to examine same microstructural areas throughout ion irradiation. A 12 wt% Cr Ferritic/Martensitic steel (HT9) was irradiated in the TEM to 1.17 x 10(20) ions.m(-2) at 440 degrees C...
Duplex stainless steels are desirable for use in power generation systems because of their attractive combination of strength, corrosion
resistance and cost. However, thermal embrittlement at intermediate homologous temperatures of ~475 °C and below, limits upper service temperatures
for many applications. New lean grade duplex alloys have improved thermal stability...
Full Text:
nuclear power
applications. ActaMaterialia, 87, 15-24. doi:10.1016/j.actamat.2014.12.012
10.1016
The thermal degradation of structural materials is considered to be a key factor for evaluating the lifetime of current nuclear power plants. Ni-based and Fe-based alloys, such as 690, 625, 304, and 316, are widely used in nuclear industry as structural components due to the extraordinary corrosion resistance and mechanical...
Because of its attractive material properties like high hardness, high toughness, and excellent high temperature strength, materials like silicon nitride are becoming more common for use in high performance applications. However, there have been limited studies of the fatigue behavior of small cracks in silicon nitride and other materials toughened...
Bulk metallic glasses (BMGs) offer a great deal of potential through their near-theoretical strength, potentially high toughness and unique forming and molding traits. However, there are still a number of outstanding issues that bar their widespread use. This thesis describes the investigation of three research questions each designed to further...
Toughened ceramics, or bridging ceramics, are being developed in an attempt
to widen the application base of traditional ceramics, which are brittle and have low
resistance to crack extension. The crack growth resistance of these extrinsically
toughened ceramics has been shown to increase with crack length, and unlike
traditional ceramics,...
The phases of transition alumina are scientifically interesting due to their high specific surface area, favorable acid/ base characteristics, and chemical and hydrothermal stability which make this metallic oxide a prime candidate for use as a support for metallic nanoparticles (NPs) in heterocatalysis. Interactions at alumina/Pt interfaces are important for...
Directed energy deposition and laser cladding technologies are suitable advanced manufacturing techniques for applying corrosion-resistant claddings to large carbon steel components. In this work, we clad 309L stainless steel wire onto carbon steel substrates and examine the effects of cladding parameters (laser power and travel speed) on metallurgical bonding, composition,...
The effect of ambient environment on the fatigue behavior of two Zr-Ti-Cu-Ni-Be bulk metallic glasses (BMGs) is examined in the present study. The first metallic glass, Zr₄₄Ti₁₁Ni₁₀Cu₁₀Be₂₅, was tested to establish the presence of an environmental effect in the fatigue growth curve measured in ambient air. Fatigue growth curves produced...
Metallic glasses (MGs) have attracted tremendous attention because of their unique properties and potential applications in the future industry. However, it is still a mystery for people to understand the formation mechanism of the bulk MGs (BMGs). To produce BMGs, the specific composition of materials, sufficiently high cooling rate, etc.,...
Electric power needs will only grow over the next decades as more humans ascend from poverty into the middle class. Currently, the majority of electric power is generated by burning fossil fuels. To help mitigate the undesirable effects of burning fossil fuels research is being done to increase the efficiency...
Metallic glasses (MGs), also called amorphous metals, are metals or metallic alloys trapped in a disordered glassy state. Their amorphous nature and absence of features such as crystal lattices and defects (dislocations, grain boundaries etc.) endows them with a host of properties that far surpass those of common crystalline materials....
Porous silicon oxycarbide (SiOC) beads were prepared by freeze-drying of water-in-oil (w/o) emulsion, containing water and polycarbosilane (PCS) dissolved p-xylene in the presence of sodium xylenesulfonate (SXS) as an emulsifier. The emulsion was frozen by being dropped onto a liquid N₂ bath, which resulted in 1~2 mm sized beads. After...
Metallic glasses are attracting tremendous attention because of their fundamental significance and great potential to be used as structural or functional materials in engineering applications. Significant efforts have been devoted to studying their unique properties as well as their disordered nature. Metallic glasses possess much higher strength and elastic strain...
Metallic glasses (also referred to as amorphous metals) have been gaining interest in the materials science community in recent years. These amorphous materials demonstrate promising properties compared to their crystalline counterparts that include much higher strength and elastic strain limit, better corrosion and wear resistance, superior soft magnetism, and an...
Low carbon steels (LCS) due to their high strength-to-cost ratio are one of the most ubiquitous materials used for a wide range of applications, including but not limited to automotive, construction, and transportation. However, the low corrosion resistance of LCS in neutral, acidic, or saline environments limits its utilization and...
Silicon carbide (SiC) and aluminum nitride (AlN) exhibit a combination of thermal and mechanical properties that are relevant to applications in electronics, aerospace, defense and automotive industries. However, the successful translation of these properties into final applications lies in the net-shaping of these ceramics into fully dense microstructures. Increasing the...
Having a series of excellent properties, the oxide dispersion-strengthened (ODS) steels provide promising solutions for the challenges of structural materials in nuclear energy, especially the development of future advanced nuclear fission and even fusion reactors. The current manufacturing route for ODS alloys includes mechanical alloying (MA) of master alloys or...
Spontaneous quasicrystal (QC) formation has not been observed in pure metals either in computation or in experiments (excluding epitaxial growth of thin atomic layers on a QC template). In this thesis work, dodecagonal QC (DDQC) grains are first discovered to spontaneously form during thermal devitrification of pure tantalum (Ta) metallic...
The miniaturization of Microtechnology-based Energy, Chemical and Biological Systems (MECS) is made possible by the use of high aspect ratio microchannel arrays to increase the surface-area-to-volume ratio of the flow conduits within the devices, resulting in an improvement in the heat and mass transfer performance of the devices. However, advantages...
Deformation of metallic glasses requires the existence of free volume to allow atomic movement under mechanical loading. Accordingly, the present research seeks to understand how free volume variations in alloys of identical compositions affect the fatigue and fracture behavior. By annealing below the glass transition temperature, the free volume of...
This paper discusses the fundamentals of a novel hybrid method to synthesize oxide dispersion strengthened (ODS) 304 L stainless steel (SS) alloy using a modified laser powder bed fusion (LPBF) machine. Previously, ODS metal matrix composites have been produced by LPBF via ball-milling, which is expensive to scale. Here, we selectively...
This study computationally and experimentally examines the mechanisms of crack penetration, deflection and the transition between penetration and deflection. The finite element analysis based computational modeling work used strength-and-energy based cohesive-zone approach to study the effect of dimensionless parameters (e.g., interfacial incident angle, fracture-length scale, and normalized toughness) on penetration/deflection...
Metallic foams have become widely available and have unique properties
that make them attractive for use in a variety of engineering applications. Due to
their complex structure, the behavior of foams under complex loading conditions
is a subject of continued research.
Digital volume correlation is a technique wherein full-field strains...
Thermoelectric materials are playing an increasingly significant role in the global effort to develop sustainable energy technologies. Consequently, the demand for materials with greater thermoelectric efficiency has stimulated the development of state-of-the-art interstitially doped skutterudite-based materials. However, since intermetallics are often embrittled by interstitial substitution, optimal skutterudite-based device design, manufacture,...
The development of methods to increase sintered density and improve dimensional tolerances is
a crucial issue in powder metallurgy and ceramic processing. Increasing the packing density of
starting powders is one effective route to achieve high sintered density and dimensional
precision. The current paper presents an in-depth study on the...
Laser Powder Bed Fusion (LPBF) is a process commonly used to create additively manufactured metal parts. The flexibility and complexity allowed by the LPBF process provides opportunity for significant advancement in multiple industries as parts can be customized in shape and function for specific needs. These benefits can be compounded...
Among recently found multi-component Zr-based bulk metallic glasses (BMG), Zr₅₈.₅Cu₁₅.₆Ni₁₂.₈Al₁₀.₃Nb₂.₈ is characterized by its lower critical cooling rate requirement and absence of beryllium as one of the constituent element which makes its handling more convenient. Its large supercooled liquid regions made possible the study of thermodynamics and kinetics of this...
Current methods in traction force analysis rely on a homogeneous extra-cellular matrix and
embedded microbeads to track deformations. The efficacy of these methods decreases when the matrix is not homogeneous. In heterogeneous matrices, beads often aggregate in regions of higher matrix density and float in regions where matrix substrate is...
We present a methodology for creating a simulated foam microstructure for use in forward simulations of wave equations to quantitatively analyze the expected scattering phenomenon primarily responsible for the attenuation of interrogating signals in Sprayed-On Foam Insulation (SOFI). Our approach builds off of the popular use of Voronoi Tessalations for...
Fe25Co25Ni25Cr25-XMoX High Entropy Alloys were fabricated in mini arc-melter and then cast into 4mm diameter cylinders by injection casting technique and 1cm diameter cylinders by water quenching technique. Heat transfer modeling during solidification of FeCoNiCr HEA was simulated. Combining X-Ray Diffraction, Optical Microscopy, Scanning Electron Microscope, Energy Dispersive X-ray analysis,...
Nanostructured ceramics offer significant improvements in properties over the
corresponding materials with grain sizes on the order of tens to hundreds of microns.
Silicon carbide (SiC) is an important structural ceramic whose properties can
potentially be enhanced due to nanoscale microstructures. It has been suggested that
SiC samples with grain...
Thermoelectric materials are playing a larger role in the global effort to
develop diverse, efficient, and sustainable energy technologies: primarily through
power-generating thermoelectric modules. The principal components of
thermoelectric modules are solid-state thermoelectric materials – typically heavily
doped semiconductors – that convert heat directly into electricity. However, this
conversion efficiency...
Transient liquid-phase diffusion brazing is used in precision, hermetic joining applications as a replacement for diffusion bonding to reduce cycle times, reduce bonding pressure and improve yields. Studies showed that the interlayer used in diffusion brazing can be detrimental due to the use of melting point depressants (MPDs). The goal...
It has been well established that ferroelectric to relaxor crossover in piezoelectric ceramics exhibit promising electromechanical and dielectric properties over a wide temperature range, applying sensors and actuators transducers and such. A plethora of research has reported giant strain in various lead-free piezoelectric ceramics and attributed the reasoning to the...
The corrosion and passivity of iron (and carbon steel) in media with different alkalinity as well as iron depassivation have been studied extensively using electrochemical methods and nano-scale surface characterization studies. The electrochemical techniques provide valuable information about the average electrochemical behavior of relatively large metal surfaces, typically in centimeter-square...
Much recent research has focused on the development lead-free perovskite piezoelectrics as environmentally compatible alternatives to lead zirconate titanate (PZT). Two main categories of lead free perovskite piezoelectric ceramic systems were investigated as potential replacements to lead zirconate titanate (PZT) for actuator devices. First, solid solutions based on Li, Ta,...
Micro- and nanotechnologies are promising advancements across many industrial sectors, including alternative energy, chemical processing, and healthcare. In particular, a focus of research has been in manufacturing process development aimed at microdevice cost reduction and quality improvement. Microdevices take advantage of enhanced heat and mass transfer to improve energy and...
Nanoscale Instrumented Indentation Testing (IIT) is a material characterization technique that is used to determine mechanical properties. The size effects present at this scale make it difficult to expand findings to a bulk scale. Modeling can be used to bridge this gap and better understand nanoscale IIT and the size...
Deep rolling is a surface finishing technique that is widely used in several industries, specifically aerospace and automotive. Extending fatigue life by inducing compressive residual stresses at and below the deep rolled surface has been the primary driving force behind this newfound popularity. Understanding the development of the residual stresses...
To assess the conversion and embedment of yttrium nitrate to yttrium oxide using selective laser melting, a thermodynamic approach for laser power and scan speed predictions on surface temperature, recoil pressure, and resulting track morphology window are employed. Inkjet printing is used to deposit the liquid film of yttrium nitrate...
Mechanical property degradation due to isothermal ageing is of potential concern for alloys based on the Ni-Cr binary system (e.g., Inconel 690, 625), particularly in nuclear power applications where component lifetimes can exceed 40 years. In the present research, the disorder-order phase transformation, which is the primary mechanism of ageing,...
This work investigates the relationship between the local structure and physical properties of a set of classical (MgTiO3, CaTiO3, SrTiO3, and BaTiO3) and complex ((1-x)Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3[BZT-BCT], Na0.5Bi0.5TiO3 [NBT]) perovskite electroceramics. The materials in this work were synthesized via standard solid state ceramic synthesis, the structure was investigated through a number of...
The motivation for undertaking this research was to increase the understanding of processing colloidal semiconductor nanocrystals and thin films metallic glasses to enable their wider application in future devices. This research covered two unique materials, lead selenide (PbSe) nanocrystals and thin film metallic glass alloy of zirconium copper aluminum nickel...
The influence of shear rate and temperature on the viscosity and fragility of the Zr₄₁.₂Ti₁₃.₈Cu₁₂.₅Ni₁₀.₀Be₂₂.₅ (Vit1) metallic glass forming liquid is measured in the liquid and undercooled liquid state between 907 and 1300 K. The results show a complex rheological behavior of Vit1. The viscosity of Vit1 is about three...
Microchannel arrays are being developed across a wide spectrum of microfluidic applications including blood processing, fuel cells and thermal management among many others. Typical arrays are based on a flat laminated architecture produced in a vacuum hot press (VHP) through solid-state diffusion bonding. Due to the cylindrical nature of certain...