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Review Article
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High-throughput and data-driven machine learning techniques for discovering high-entropy alloys
High-entropy alloys exhibit attractive property combinations. This review paper discusses the use of the materials genome strategy for identifying promising high-entropy alloys, including high-throughout synthesis, characterization, and data-driven machine learning.
- Lu Zhichao
- , Ma Dong
- & Zhaoping Lu
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Article
| Open Access
Martensite decomposition during rapid heating of Ti-6Al-4V studied via in situ synchrotron X-ray diffraction
Martensite in Ti-6Al-4V is known to decompose under heating. This study employs rapid laser heating in situ in a synchrotron to study changes in the diffraction profiles during the martensite decomposition process.
- Seunghee A. Oh
- , Joseph W. Aroh
- & Anthony D. Rollett
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Article
| Open Access
Tailoring hierarchical microstructures and nanoprecipitates in additive-manufactured Al-Zn-Mg-Cu-Nb alloys for simultaneously enhancing strength and ductility
Additive manufacturing is known to create microstructures that cannot be achieved by conventional alloy processing. Here, heat treatment of an additively-manufactured aluminum alloy creates a hierarchical microstructure with a large number of precipitates, achieving high strength and ductility.
- Fei Xiao
- , Da Shu
- & David H. StJohn
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Article
| Open Access
The role of stacking fault tetrahedra on void swelling in irradiated copper
Irradiation-induced void swelling is known to be higher in metals with an fcc structure compared to bcc, though the reason behind this is unclear. Here, by combining simulations and STEM imaging, stacking fault tetrahedra are found to be the cause of a high swelling rate in fcc copper.
- Ziang Yu
- , Yan-Ru Lin
- & Haixuan Xu
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Article
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Continuous iron spreading on carbon-shell composite nanotubes for electromagnetic wave absorption
The high aspect ratio of nanotubes makes them effective for electromagnetic wave absorbing materials. Here, a carbon shell is synthesized on the surface of iron-based nanotubes, achieving a composite with electromagnetic properties and impedance that are suitable for electromagnetic shielding.
- Yuanyuan Zhang
- , Yining Li
- & Jiantang Jiang
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Article
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Revealing per-grain and neighbourhood stress interactions of a deforming ferritic steel via three-dimensional X-ray diffraction
The response of a polycrystalline material during loading is strongly dependent on grain-level effects, such as residual stress from plasticity and grain orientation. Here, in-situ three-dimensional X-ray diffraction reveals the role of local and interacting grain stresses in a ferritic steel.
- James A. D. Ball
- , Anna Kareer
- & David M. Collins
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Article
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Cathodic protection mechanism of iron and steel in porous media
Cathodic protection is widely used in protecting structures from corrosion, but its working mechanism remains unclear. Here, in-situ and ex-situ characterization techniques, coupled with electrochemical measurements, are used to study the spatio-temporal changes at the steel-electrolyte interface.
- Federico Martinelli-Orlando
- , Shishir Mundra
- & Ueli M. Angst
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Article
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Additive manufacturing of defect-free TiZrNbTa refractory high-entropy alloy with enhanced elastic isotropy via in-situ alloying of elemental powders
Refractory high-entropy alloys are attractive for high-temperature applications, but are challenging to process. Here, a method is shown for identifying a processing window that allows the additive manufacturing of a TiZrNbTa refractory alloy with a low defect content and mechanical properties comparable to as-cast samples.
- Shahryar Mooraj
- , George Kim
- & Wen Chen
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Article
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Overcoming strength-toughness trade-off in a eutectic high entropy alloy by optimizing chemical and microstructural heterogeneities
Overcoming the strength-toughness trade-off is a key goal of alloy engineering. Here, a two-phase eutectic high entropy alloy is reported that harnesses microstructural and chemical heterogeneity to achieve high toughness and ductility.
- Zhaoqi Chen
- , Wenqing Zhu
- & Yong Yang
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Article
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Curvature tuning through defect-based 4D printing
4D printing techniques enable the realization of smart materials whose shape or properties can change with time. Here, utilizing the anisotropic deformation of a combination of polymers and the distribution of microdefects formed during the 3D printing process, the authors realize a variety of shape-changing curved structures that can be used in drug delivery systems.
- Vahid Moosabeiki
- , Ebrahim Yarali
- & Amir A. Zadpoor
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Article
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Segregation-induced strength anomalies in complex single-crystalline superalloys
The segregation of elements in superalloys is known to influence their mechanical properties. Here, atomic-scale imaging and theoretical calculations reveal a mechanism by which segregation causes a yield strength anomaly, strengthening the superalloy.
- Andreas Bezold
- , Jan Vollhüter
- & Steffen Neumeier
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Article
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Unlocking the potential of ordinary Portland cement with hydration control additive enabling low-carbon building materials
Ordinary Portland cement is a commonly used construction material but contributes to high carbon emissions. Here, a hydration control additive can modify the kinetics of ordinary Portland cement to increase its strength, potentially reducing the amount of cement needed.
- Xuerun Li
- , Harald Grassl
- & Joachim Dengler
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Article
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Processable crosslinked terpolymers made from elemental sulfur with wide range of thermal and mechanical properties
The thermal and mechanical properties of inverse vulcanized polymers are currently underdeveloped. Here, a series of terpolymers copolymerized from two distinct organic comonomers and elemental sulfur yield polymers with a wide range of glass transition temperatures and show good mechanical properties.
- Peiyao Yan
- , Haoran Wang
- & Tom Hasell
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Article
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Dendritic deformation modes in additive manufacturing revealed by operando x-ray diffraction
In-situ x-ray studies have proven to be vital in understanding solidification behavior during additive manufacturing of alloys. Here, operando synchrotron diffraction of a superalloy reveals the effects of solidification dynamics on dendrite deformation mechanisms during laser melting.
- Adrita Dass
- , Chenxi Tian
- & Atieh Moridi
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Article
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Algorithm for fast evaluation of in-plane fiber orientation in reinforced plastics using light microscopy images
The orientation of reinforcing fibers in composite materials is key to their performance, yet is hard to determine as fibers are buried within a sample. Here, an algorithm allows for the rapid determination of in-plane fiber orientation, based on microscopy images of adjacent regions.
- Klara Wiegel
- , André Schlink
- & Hans-Peter Heim
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Article
| Open Access
Operando tomographic microscopy during laser-based powder bed fusion of alumina
Understanding the effects of changing process parameters during additive manufacturing is vital for building high-quality parts. Here, operando tomographic microscopy during laser-based processing of alumina reveals detailed insight into process dynamics, including melt pool behavior and defect formation.
- Malgorzata G. Makowska
- , Fabrizio Verga
- & Steven Van Petegem
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Article
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Three-dimensional reconstruction and computational analysis of a structural battery composite electrolyte
Structural battery composites contain a porous solid phase that holds the structural integrity of the system with a liquid phase in the pores. Here, the porous structure is studied using combined focused ion beam and scanning electron microscopy and transferred into finite element models.
- Shanghong Duan
- , Martina Cattaruzza
- & Leif E. Asp
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Article
| Open Access
Additive manufacturing of a high-performance aluminum alloy from cold mechanically derived non-spherical powder
Additive manufacturing typically uses spherical powder feedstock prepared by gas or plasma atomization. Here, a high-performance aluminum alloy is prepared from cold mechanically derived powder, showing the viability of non-spherical powders for good mechanical properties.
- J. Hunter Martin
- , John E. Barnes
- & David F. Bahr
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Article
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Bio-inspired selective nodal decoupling for ultra-compliant interwoven lattices
Architected materials are known for high stiffness-to-weight behavior but bending-dominated lattices are of interest for their energy absorption performance. Here, an interwoven lattice with decoupled nodes shows significantly higher compliance at similar volume fractions to traditional lattices
- Yash Mistry
- , Oliver Weeger
- & Dhruv Bhate
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Article
| Open Access
Strong conformable structure via tension activated kirigami
Kirigami, the art of deploying flat sheets to create three-dimensional structures, relies often on complex folding processes that hinder industrial applications. Here, the authors develop a folding-wall kirigami pattern that deploys easily under tension, demonstrating its strength, stiffness, energy absorption, and interlocking properties.
- Tom Corrigan
- , Patrick Fleming
- & Delony Langer-Anderson
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Article
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Strong and tough magnesium-MAX phase composites with nacre-like lamellar and brick-and-mortar architectures
Lamellar and brick-and-mortar microstructures mirror those of naturally occurring nacre and are known for their good mechanical performance. Here, magnesium-MAX composites are created with either a lamellar or brick-and-mortar microstructure, resulting in high strength and toughness.
- Yanyan Liu
- , Xi Xie
- & Robert O. Ritchie
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Article
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Dislocation loop bias and void swelling in irradiated α-iron from mesoscale and atomistic simulations
Dislocation loop bias is ubiquitous in irradiated materials but complicated dislocation loop and point defect interactions make evaluation of dislocation loop bias factors difficult. Here, an atomistic approach based on α-iron point defect lifetimes is developed that allows mechanistic understanding.
- Ziang Yu
- & Haixuan Xu
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Article
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Fabrication of helix–fiber composites with mechanically coupled core-wrapping for programmable properties
Helix-fiber composites are used in intelligent stretchable materials but current understanding is still lacking. Here, we show that mechanical coupling plays a critical role in controlling structural properties and demonstrate use as an elastic conductor, sensor, and structure transplantation.
- Dan Li
- , Zhiwei Zhu
- & Yu Wang
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Article
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The influence of lattice misfit on screw and edge dislocation-controlled solid solution strengthening in Mo-Ti alloys
In body-centered cubic alloys, screw dislocations are considered to be strength-controlling. Here, a systematic investigation of Mo-Ti alloys with varying lattice misfit reveals a transition from screw to edge dislocation-controlled strength.
- Georg Winkens
- , Alexander Kauffmann
- & Martin Heilmaier
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Article
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Evading dynamic strength and ductility trade-off in a high-entropy alloy via local chemical ordering
Local chemical ordering has been shown to improve the mechanical properties of high-entropy alloys. Here, Zr- and (Nb, Ta)-locally enriched ordering is found to enhance both the dynamic strength and ductility of a TiZrNbTa high-entropy alloy under high strain rate loading.
- Ruixin Wang
- , Dabo Duan
- & Zhaoping Lu
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Article
| Open Access
Probing the composition dependence of residual stress distribution in tungsten-titanium nanocrystalline thin films
Nanocrystalline thin films fabricated by deposition often have high residual stresses, making them susceptible to defects. Here, stress distribution in tungsten-titanium nanocrystalline films are probed by experimental and simulation techniques, revealing the impact of solute concentration on residual stress.
- Rahulkumar Jagdishbhai Sinojiya
- , Priya Paulachan
- & Roland Brunner
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Article
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High frequency beam oscillation keyhole dynamics in laser melting revealed by in-situ x-ray imaging
Beam oscillation is an attractive method to achieve melt pool and microstructure control in laser powder bed additive manufacturing. Here, in-situ X-ray imaging and high-fidelity modeling reveal the unique keyhole dynamics in a kHz laser oscillation mode.
- Ziheng Wu
- , Guannan Tang
- & Anthony D. Rollett
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Article
| Open Access
Effective medium theory for the low-temperature heat capacity of a metasolid plate
Modeling artificial nanostructures in terms of effective materials parameters is important for gaining physical insight into their behavior and facilitating their optimization. Here, an analytical effective medium theory for the heat capacity of holey phononic crystals is derived, revealing the effect of the emergent anisotropic elastic response of the metasolid.
- Tuomas A. Puurtinen
- & Ilari J. Maasilta
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Article
| Open Access
Selective hinge removal strategy for architecting hierarchical auxetic metamaterials
Pivotally interconnected polygons are capable of auxetic behavior, but have not been fully explored. Here, a design method is demonstrated based on the selective removal of rotational hinges in pivotally interconnected polygons with even-numbered modules, leading to fully-deployable structures.
- Ehsan Jalali
- , Hadi Soltanizadeh
- & Pooya Sareh
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Article
| Open Access
Fatigue fracture mechanism of amorphous materials from a density-based coarse-grained model
Fracture during fatigue loading is known to occur in materials for small strains, below the yield strain. Here, coarse-grain simulations of a model amorphous material reveals that the onset strain at which irreversible deformation occurs is the same for fatigue as it is for monotonic loading.
- Yuji Kurotani
- & Hajime Tanaka
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Article
| Open Access
Coexistence of two types of short-range order in Si–Ge–Sn medium-entropy alloys
Short-range chemical ordering has emerged as a key feature for controlling the properties of high-entropy alloys. Here, ab initio calculations reveal that two types of short-range ordering exist in Si–Ge–Sn medium-entropy alloys, suggesting that multiple types of ordering could exist in a single alloy.
- Xiaochen Jin
- , Shunda Chen
- & Tianshu Li
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Article
| Open Access
Shear band formation during nanoindentation of EuB6 rare-earth hexaboride
Rare-earth hexaborides are of interest for their pressure-induced phase transformations, but further understanding is needed regarding their failure mechanisms. Here, nanoindentation of EuB6 causes dislocation-mediated shear band formation, driven by the breaking of boron-boron bonds.
- Rajamallu Karre
- , Yidi Shen
- & Kolan Madhav Reddy
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Article
| Open Access
Dual Kondo effect charge ordering and zero thermal expansion in a correlated intermetallic
Theoretical studies have predicted a Kondo effect driven charge density wave order with two sublattices characterized by different single-ion Kondo temperatures. Here, X-ray photoemission spectroscopy provides evidence of a dual Kondo effect in the charge ordered phase of YbPd, elucidating the mechanism of its zero thermal expansion.
- Yen-Fa Liao
- , Bodry Tegomo Chiogo
- & Ashish Chainani
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Article
| Open Access
Identifying chemically similar multiphase nanoprecipitates in compositionally complex non-equilibrium oxides via machine learning
Characterizing fission products in uranium dioxide nuclear fuel is important for predicting its long-term properties. Here, machine learning is used to mine microscopy images of precipitates and nanoscale gas bubbles in high-burn-up fuels, providing detailed structural insight of nanoscale fission products.
- Keyou S. Mao
- , Tyler J. Gerczak
- & Philip D. Edmondson
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Article
| Open Access
Corrosion resistant and high-strength dual-phase Mg-Li-Al-Zn alloy by friction stir processing
Mg-Li alloys are attractive for their low density, yet typically suffer from limited strength and rapid corrosion. Here, both these issues are addressed in a Mg-Li-Al alloy by friction stir processing followed by liquid CO2 quenching, resulting in a durable microstructure.
- Zhuoran Zeng
- , Mengran Zhou
- & Nick Birbilis
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Article
| Open Access
Cavity vat photopolymerisation for additive manufacturing of polymer-composite 3D objects
There is an ongoing drive for new additive manufacturing processes that produce complex parts. Here, cavity vat polymerisation is introduced, in which cavities are filled with a dual-curing resin that forms an elastomer/thermoset covalently bonded interface, creating hard-shell/soft-core parts.
- Joel Bachmann
- , Philip Obst
- & Olaf Hinrichsen
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Article
| Open Access
Utilizing local phase transformation strengthening for nickel-base superalloys
There is an ongoing need to increase the operating temperature of jet engines, requiring new high-temperature materials. Here, local phase transformations at superlattice stacking faults contribute to a three times improvement in creep strength in a Ni-based superalloy.
- Timothy M. Smith
- , Nikolai A. Zarkevich
- & Michael J. Mills
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Article
| Open Access
4D Thermomechanical metamaterials for soft microrobotics
4D metamaterials offer the additional functionality of being responsive to external stimuli. Here, a metamaterial-based soft robot is composed of bilayer plates that can rotate and translate in response to thermal stimuli, allowing controlled motion.
- Qingxiang Ji
- , Johnny Moughames
- & Muamer Kadic
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Article
| Open Access
Periodic island-layer-island growth during deposition of ultrastable metallic glasses
Ultrastable metallic glasses form by surface diffusion on a substrate during deposition. Here, this process is shown to involve the collective diffusion of atoms in a cyclic process, involving the formation of islands, their coalescence into a layer, followed by further island formation.
- Fan Yang
- , Chao Wang
- & Yanhui Liu
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Article
| Open Access
Adaptive bidirectional extracellular electron transfer during accelerated microbiologically influenced corrosion of stainless steel
Microbiologically influenced corrosion is a major source of degradation of metals. Here, extracellular electron transfer is studied during pitting corrosion of stainless steel in the presence of an electroactive bacterium and a riboflavin electron shuttle, revealing bidirectional electron transfer.
- Ziyu Li
- , Weiwei Chang
- & Xiaogang Li
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Article
| Open Access
Physical and chemical imaging of adhesive interfaces with soft X-rays
Understanding adhesion mechanisms for polymer composites is challenging due to the bonded interface being buried. Here, soft X-rays are used to probe the chemical and physical nature of the interface, revealing multiscale factors that influence the adhesion mechanism and bond strength.
- Hiroyuki Yamane
- , Masaki Oura
- & Takaki Hatsui
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Article
| Open Access
Enhanced aging kinetics in Al-Mg-Si alloys by up-quenching
Thermal treatments are important for controlling the microstructure and mechanical properties of precipitation-hardened alloys. Here, an up-quenching process enhances clustering kinetics in an Al-Mg-Si alloy, attributed to retained high temperature vacancies assisting diffusion at low temperature.
- Florian Schmid
- , Philip Dumitraschkewitz
- & Stefan Pogatscher
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Article
| Open Access
Enhanced electrical conductivity and mechanical properties in thermally stable fine-grained copper wire
Strength and electrical conductivity are generally mutually exclusive properties in copper wires, both of which are required in applications such as high-speed rail. Here, rotary swaging is used to manufacture copper wires that combine high strength and conductivity, and are thermally stable.
- Qingzhong Mao
- , Yusheng Zhang
- & Yonghao Zhao
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Article
| Open Access
Cryogenic toughness in a low-cost austenitic steel
Most alloys become mechanically brittle at very low temperatures. Here, an austenitic Fe-30Mn-0.11C steel exhibits high toughness, strength and elongation at liquid nitrogen temperatures, reaching a Charpy impact toughness of 453 J.
- Yuhui Wang
- , Yubin Zhang
- & Xiaoxu Huang
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Article
| Open Access
Fish-inspired flexible protective material systems with anisotropic bending stiffness
Armored fish exoskeletons combine flexibility and protection from predators and territorial attacks. Here, using modeling, 3D printing, and experimental testing, the mechanical origin of anisotropic bending stiffness in fish scale architectures is revealed, providing design guidelines for biomimetics.
- Katia Zolotovsky
- , Swati Varshney
- & Christine Ortiz
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Article
| Open Access
Thermodynamic model for lattice point defect-mediated semi-coherent precipitation in alloys
Precipitation of secondary phases in a crystalline matrix often leads to the loss of coherency at the phase boundary. Here, a thermodynamic model for precipitation is presented that takes into account the role of lattice point defects on the accommodation mechanism of coherency loss.
- Maylise Nastar
- , Lisa T. Belkacemi
- & Marie Loyer-Prost
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Article
| Open Access
Atomic resolution imaging of cation ordering in niobium–tungsten complex oxides
Niobium-tungsten complex oxides have recently received interest for their use as energy storage materials in lithium-ion batteries. Here, atomic-resolution electron microcopy reveals their structure, including cation ordering.
- Sumio Iijima
- , Wenhui Yang
- & Ichiro Ohnishi
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Article
| Open Access
Atomic-scale homogeneous plastic flow beyond near-theoretical yield stress in a metallic glass
Metallic glasses display a high yield strength and typically deform via heterogeneous shear bands beyond the yield point. Here, deformation of as little as 1000 atoms in a Pt-based metallic glass at room temperature leads to near-theoretical yield strength, beyond which homogeneous deformation occurs.
- Jiaxin Yu
- , Amit Datye
- & Udo D. Schwarz
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Article
| Open Access
Enhancing ductility in bulk metallic glasses by straining during cooling
Bulk metallic glasses typically display limited ductility. Here, straining a bulk metallic glass during cooling from the supercooled region is shown to enhance bending ductility, attributed to the structure being pulled up the potential energy landscape.
- Rodrigo Miguel Ojeda Mota
- , Ethen Thomas Lund
- & Jan Schroers
In situ observation and reduction of hot-cracks in laser additive manufacturing