Featured
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| Open AccessStrong graphene oxide nanocomposites from aqueous hybrid liquid crystals
Reinforcing polymers with carbon-based nanofillers is non-trivial due to incompatibilities between matrix and filler. Here, the authors report highly reinforced graphene oxide–aramid nanocomposites utilizing a water-based hybrid biaxial nematic mixture.
- Maruti Hegde
- , Lin Yang
- & Theo J. Dingemans
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Article
| Open AccessThe role of side-branching in microstructure development in laser powder-bed fusion
Understanding metal component microstructure during 3D printing remains a challenge. Here, the authors use local thermal parameters and the solidification microstructure to better understand how the printed microstructure varies with the laser scan strategy.
- Minh-Son Pham
- , Bogdan Dovgyy
- & Alessandro Piglione
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Article
| Open AccessControlling solid-liquid interfacial energy anisotropy through the isotropic liquid
In metals, dendrite orientation during crystal growth has been hypothesized to be affected by compositional additions. Here, the authors combine molecular dynamics and experiments in the aluminium-samarium system to prove solute atoms can affect dendrite orientation via interfacial energy changes.
- Lei Wang
- , Jeffrey J. Hoyt
- & Chad W. Sinclair
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Article
| Open AccessAlloying design of biodegradable zinc as promising bone implants for load-bearing applications
Biodegradable implants are of great interest in orthopaedic applications but have been limited by low mechanical strength. Here, the authors examine systematically in detail the strengthening of biodegradable zinc by alloying with beneficial elements using mechanical, biodegradability and biocompatibility testing.
- Hongtao Yang
- , Bo Jia
- & Yufeng Zheng
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Article
| Open AccessUnveiling the Re effect in Ni-based single crystal superalloys
Adding minute amounts of rhenium to Ni-based single crystal superalloys extends their high temperature performance in engines, but the reasons behind that are still unclear. Here, the authors combine high resolution imaging and modelling to show that rhenium enriches and slows down partial dislocations to improve creep performance.
- Xiaoxiang Wu
- , Surendra Kumar Makineni
- & Baptiste Gault
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Article
| Open AccessLamellar architectures in stiff biomaterials may not always be templates for enhancing toughness in composites
Nacre is a biological composite whose architecture greatly enhances its toughness. Here, the authors report on the toughness enhancement in the spicules of a marine sponge. The spicules display similar architecture to nacre; however, their architecture does not lead to similar toughness enhancement.
- Michael A. Monn
- , Kaushik Vijaykumar
- & Haneesh Kesari
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Article
| Open AccessTwo-way tuning of structural order in metallic glasses
While metallic glasses are expected to have tunable structures, these have rarely been demonstrated. Here, the authors combine temperature and pressure to show a two-way structural tuning in rare earth-based metallic glasses beyond the nearest-neighbor atomic shells.
- Hongbo Lou
- , Zhidan Zeng
- & Qiaoshi Zeng
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Article
| Open AccessNested helicoids in biological microstructures
Helicoids are common structures found in many structural biological materials. Here, the authors report on a study of helicoids in the claws of scorpions and report different microstructures to what have previously been reported which have implications in materials stiffness, strength and toughness.
- Israel Greenfeld
- , Israel Kellersztein
- & H. Daniel Wagner
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Article
| Open AccessGrain structure control during metal 3D printing by high-intensity ultrasound
3D printing of metals produces elongated columnar grains which are usually detrimental to component performance. Here, the authors combine ultrasound and 3D printing to promote equiaxed and refined microstructures in a titanium alloy and a nickel-based superalloy resulting in improved mechanical properties.
- C. J. Todaro
- , M. A. Easton
- & M. Qian
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Article
| Open AccessHydroxyl-rich macromolecules enable the bio-inspired synthesis of single crystal nanocomposites
Calcium carbonate biomineralisation has long been linked to acidic macromolecules. Here, the authors challenge this view and show that a huge number of gold nanoparticles coated with hydroxyl-rich proteins can be incorporated into a calcium carbonate crystal while maintaining single crystal character.
- Yi-Yeoun Kim
- , Robert Darkins
- & Fiona C. Meldrum
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Article
| Open AccessBioinspired design of flexible armor based on chiton scales
Biology has often served as the inspiration for the design of body armor; one common limitation is the flexibility of the resultant armor. Here, the authors examine the armour of chiton and use the observed design principles to 3D print flexible armor.
- Matthew Connors
- , Ting Yang
- & Ling Li
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Review Article
| Open AccessTailoring heterogeneities in high-entropy alloys to promote strength–ductility synergy
High entropy alloys are a departure from conventional alloy design. In this review, the authors examine how combinations of hetererogeneities specific to high entropy alloys can overcome the strength–ductility trade-off inherent to traditional alloys.
- Evan Ma
- & Xiaolei Wu
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Article
| Open AccessStructural order as a genuine control parameter of dynamics in simple glass formers
The glass-forming materials exhibit dynamical slowing down together with spatial heterogeneity at microscales, but their origin remains debated. Tong and Tanaka show that this phenomenon can be unified based on a structural order parameter capable of detecting subtle ordering in instantaneous liquid states.
- Hua Tong
- & Hajime Tanaka
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Article
| Open AccessExploring multistability in prismatic metamaterials through local actuation
So far, mostly 2D building blocks have been used to make origami-type multistable metamaterials that can keep their shape when deformed. Here, the authors introduce a local actuation strategy to explore the energy landscape of multistable metamaterials fabricated from 3D prismatic building blocks.
- Agustin Iniguez-Rabago
- , Yun Li
- & Johannes T. B. Overvelde
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Article
| Open AccessA transferable machine-learning framework linking interstice distribution and plastic heterogeneity in metallic glasses
Understanding plastic deformation in metallic glasses is challenging due to their heterogeneous atomic environments. Here the authors propose a machine learning approach generalizable across compositions to predict the structural features from which plastic deformation is initiated in a metallic glass.
- Qi Wang
- & Anubhav Jain
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Article
| Open AccessFast and quantitative 2D and 3D orientation mapping using Raman microscopy
Although polarized Raman microscopy is sensitive to orientation changes, quantitative information has been missing. Here, the authors use simultaneous registration of multiple Raman scattering spectra obtained at different polarizations and show quantitative orientation mapping
- Oleksii Ilchenko
- , Yuriy Pilgun
- & Anja Boisen
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Article
| Open AccessApproaching diamond’s theoretical elasticity and strength limits
While diamond is the strongest natural material, it fails to reach its theoretical elasticity limits and is brittle. Here, the authors show that thin <100>-orientated diamond nanoneedles can reach diamond’s theoretical strength and elasticity limits in tension.
- Anmin Nie
- , Yeqiang Bu
- & Wei Yang
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Article
| Open AccessArtificial spider silk from ion-doped and twisted core-sheath hydrogel fibres
Different models are believed to be the reason for the superior mechanical properties of spider silk. Here, the authors prepare artificial spider silk by water-evaporation-induced self-assembly of a hydrogel fibre made from polyacrylic acid and silica nanoparticles.
- Yuanyuan Dou
- , Zhen-Pei Wang
- & Zunfeng Liu
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Article
| Open AccessFast coalescence of metallic glass nanoparticles
The coarsening of amorphous metallic nanoparticles remains poorly understood. Here, the authors combine high resolution microscopy and atomistic simulations to show the disordered structure of amorphous nanoparticles makes them coarsen faster than crystalline ones.
- Yuan Tian
- , Wei Jiao
- & Mingwei Chen
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Article
| Open AccessDiffractive small angle X-ray scattering imaging for anisotropic structures
Mesoscale investigations of material microarchitecture using small angle X-ray scattering (SAXS) methods have been limited by long measurement times. Here, the authors present an X-ray diffractive optics method which enables single shot acquisition of SAXS signals over large areas.
- Matias Kagias
- , Zhentian Wang
- & Marco Stampanoni
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Article
| Open AccessHierarchical nanostructured aluminum alloy with ultrahigh strength and large plasticity
Strengthening a metallic alloy without sacrificing ductility remains challenging. Here, the authors develop a hierarchical nanostructured aluminium alloy composed of nanograins surrounding by metallic glass shells that has both ultrahigh strength and good ductility.
- Ge Wu
- , Chang Liu
- & Jian Lu
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Article
| Open AccessStress breaks universal aging behavior in a metallic glass
Thermal annealing of metallic glasses is known to cause a universal increase of the relaxation time with sample age. Here, however, the authors show how a mechanical stress disrupts this universal response, leading to highly non-monotonous structural dynamics with time.
- Amlan Das
- , Peter M. Derlet
- & Robert Maaß
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Article
| Open AccessRandom auxetics from buckling fibre networks
Auxetic materials have usually been developed with periodically arrange structures. Here, the authors electrospin fibre networks, and show both theoretically and experimentally that these random structures have pronounced auxetic behaviour with negative out-of-plane Poisson’s ratio of large magnitude.
- S. Domaschke
- , A. Morel
- & A. E. Ehret
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Article
| Open AccessNanoscale deformation mechanics reveal resilience in nacre of Pinna nobilis shell
Hierarchical structural materials combine organic and inorganic components to withstand mechanical impact but the nanomechanics that govern the superior properties are not well investigated. Here, the authors observe nanoscale recovery of heavily deformed nacre that restores its mechanical strength using high-resolution electron microscopy.
- Jiseok Gim
- , Noah Schnitzer
- & Robert Hovden
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Article
| Open AccessSize-dependent diffusion controls natural aging in aluminium alloys
Aluminium alloys can naturally age and form microstructural clusters that affect their mechanical properties. Here, the authors show that nanosized samples do not under undergo natural aging because diffusion-controlled clustering processes are inhibited.
- Phillip Dumitraschkewitz
- , Peter J. Uggowitzer
- & Stefan Pogatscher
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Article
| Open AccessAdvantages of eutectic alloys for creating catalysts in the realm of nanotechnology-enabled metallurgy
The combination of metallurgy concepts and nanotechnology with liquid metal processing has been largely unexplored. Here the authors use liquid-phase ultrasonication to produce a model system of catalytically active nano-alloys, demonstrating electrocatalysis and photocatalysis.
- Jianbo Tang
- , Rahman Daiyan
- & Kourosh Kalantar-Zadeh
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Article
| Open AccessNon-reciprocal robotic metamaterials
Here, the authors demonstrate a robotic metamaterial implemented through a combination of actuators, sensors and local controllers. They show that this active metamaterial can exhibit tunable linear non-reciprocal dynamic characteristics, with a very large and broadband non-reciprocal gain.
- Martin Brandenbourger
- , Xander Locsin
- & Corentin Coulais
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Article
| Open AccessLocal electronic descriptors for solute-defect interactions in bcc refractory metals
Understanding the interactions between solute atoms and crystalline defects is essential for determining alloy properties. Here the authors use a linear regression model to propose a quantitative correlation between local electronic structure descriptors and the solute-defect interaction energies in bcc refractory alloys.
- Yong-Jie Hu
- , Ge Zhao
- & Liang Qi
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Article
| Open AccessSelective crack suppression during deformation in metal films on polymer substrates using electron beam irradiation
Cracking in thin films is usually associated with failure. Here, the authors use an electron beam to selectively irradiate a copper thin film on a polymer substrate and introduce designed cracks under tension to make a strain responsive organic light-emitting device (OLED).
- So-Yeon Lee
- , Kyung Ryoul Park
- & In-Suk Choi
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Article
| Open AccessThe hidden structure of human enamel
Enamel is the hardest tissue in the body and has been widely studied, yet aspects of its structure remain unclear. Here, the authors report on a study of the orientation and alignment of enamel crystals and challenge previous assumptions.
- Elia Beniash
- , Cayla A. Stifler
- & Pupa U. P. A. Gilbert
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Article
| Open AccessMicroscale residual stresses in additively manufactured stainless steel
The impact of grain-scale residual stresses on the mechanical behaviour of 3D-printed metals and alloys remains unexplored. Here, the authors combine in situ synchrotron X-ray diffraction and computer simulations to link residual stresses in steel to its tensile behaviour.
- Wen Chen
- , Thomas Voisin
- & Y. Morris Wang
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Article
| Open AccessInvariant and smooth limit of discrete geometry folded from bistable origami leading to multistable metasurfaces
The mechanisms behind origami having saddle shapes made from concentrically pleated squares remain elusive. Here, the authors connect geometry and mechanics to show that this type of origami is invariantly a hyperbolic paraboloid that exhibits bistability between two symmetric configurations.
- Ke Liu
- , Tomohiro Tachi
- & Glaucio H. Paulino
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Article
| Open AccessAluminum with dispersed nanoparticles by laser additive manufacturing
Incorporating and dispersing dense nanoparticles into metals remains a challenge. Here, the authors use nanocomposite powders containing very dense nanoparticles to print an aluminium nanocomposite with one of the highest specific modulus and yield strength among all structural materials.
- Ting-Chiang Lin
- , Chezheng Cao
- & Xiaochun Li
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Article
| Open AccessA bioinspired hydrogen bond-triggered ultrasensitive ionic mechanoreceptor skin
Wearable pressure sensors have a range of potential applications. Here, the authors develop ion pairs decorated silica microstructures embedded in an elastomeric matrix to mimic natural skin mechanoreceptors’ functions for applications in pressure-sensitive artificial skin.
- Vipin Amoli
- , Joo Sung Kim
- & Do Hwan Kim
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Article
| Open AccessMicro-/nano-voids guided two-stage film cracking on bioinspired assemblies for high-performance electronics
Metal film-based electronics usually fail via uncontrolled cracking at small strains. Here, the authors design a micro-/nano-structured surface with bundled flexible nanowires onto which a metal film can stretch more than a regular flat surface, retard penetrating cracks and remain sensitive.
- Weining Miao
- , Yuxing Yao
- & Xiaoguang Wang
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Article
| Open AccessIntegrating tough Antheraea pernyi silk and strong carbon fibres for impact-critical structural composites
Natural silk fibres are tough, but they lack required strength and stiffness as a reinforcement for polymer matrix composites. Here, the authors hybridise silks produced by a wild caterpillar A. pernyi with high-performance carbon fibres to produce tough, strong and impact resistant composites.
- Kang Yang
- , Juan Guan
- & Robert O. Ritchie
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Article
| Open AccessUsing X-ray tomoscopy to explore the dynamics of foaming metal
Understanding fast phenomena that happen in hot and opaque environments, such as during metal foaming, remains a challenge. Here, the authors use ultra-fast imaging of more than 200 three-dimensional volumes per second to explore bubble coalescence in an aluminium alloy.
- Francisco García-Moreno
- , Paul Hans Kamm
- & John Banhart
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Article
| Open AccessShape-memory effects in molecular crystals
Molecular crystals can be bent elastically by expansion or contraction on opposite faces, or plastically by delamination into slabs that glide along slip planes. Here the authors report crystals that can be bent plastically while undergoing a mechanically induced phase transition without delamination.
- Ejaz Ahmed
- , Durga Prasad Karothu
- & Panče Naumov
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Article
| Open AccessRETRACTED ARTICLE: Mechanically interlocked architecture aids an ultra-stiff and ultra-hard elastically bendable cocrystal
Molecular crystals are typically less stiff than metals or ceramics. Here the authors report an organic elastically bendable co-crystal with stiffness comparable to low-density metals, hardness similar to stainless steel and reveal the molecular mechanism which lead to these mechanical properties.
- Somnath Dey
- , Susobhan Das
- & C. Malla Reddy
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Article
| Open AccessPlasticity without dislocations in a polycrystalline intermetallic
The deformation of materials depends on dislocation activity, and suppressing dislocations should lead to brittleness. Here, the authors combine simulations and experiments to show a samarium-cobalt intermetallic can exhibit plasticity without dislocations.
- Hubin Luo
- , Hongwei Sheng
- & Izabela Szlufarska
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Article
| Open AccessStrengthening in multi-principal element alloys with local-chemical-order roughened dislocation pathways
Multi-principal-element alloys have been assumed to have the configurational entropy of an ideal solution. Here, the authors use atomistic simulations to show that instead NiCoCr exhibits local chemical order, raising the activation barriers of dislocation activities to elevate mechanical strength.
- Qing-Jie Li
- , Howard Sheng
- & Evan Ma
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Article
| Open AccessReconfigurable soft body trajectories using unidirectionally stretchable composite laminae
Soft actuators are typically confined to a single, predetermined deformation trajectory. Here, the authors report on a bioinspired self-adhesive material which can be attached, detached, and re-attached to expanding soft bodies to render reconfigurable and controllable deformation trajectories.
- Sang Yup Kim
- , Robert Baines
- & Rebecca Kramer-Bottiglio
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Article
| Open AccessStrong stress-composition coupling in lithium alloy nanoparticles
Electrochemical reactions can generate stresses that detrimentally affect battery electrodes. Here, the authors directly image the lithiation of core-shell tin-based nanoparticles and show that lithium can be redistributed by applying stress and change the nanoparticle composition.
- Hyeon Kook Seo
- , Jae Yeol Park
- & Jong Min Yuk
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Article
| Open AccessUltrasound experiments on acoustical activity in chiral mechanical metamaterials
Here, the authors report an effect analogous to optical activity in a 3D mechanical micro-lattice composed of chiral unit cells. They spatiotemporally resolve the motion of metamaterial beams at ultrasonic frequencies with nanometric precision and show up to 22° polarization rotation per unit cell.
- Tobias Frenzel
- , Julian Köpfler
- & Martin Wegener
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Article
| Open AccessThree-dimensional character of the deformation twin in magnesium
Imaging deformation twins in three dimensions is difficult and they are usually viewed as two-dimensional ellipsoids. Here, the authors statistically analyze more than two hundred deformation twins in magnesium observed in three different views and show lateral twin expansion is faster than forward propagation.
- Y. Liu
- , P. Z. Tang
- & C. N. Tomé
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Article
| Open AccessDirect observation and impact of co-segregated atoms in magnesium having multiple alloying elements
Commercial alloys contain trace solutes that segregate at grain boundaries but have been difficult to directly image due to electron beam damage. Here, the authors use atomic-resolution energy dispersive X-ray spectroscopy at lower electron voltage to image segregation at magnesium alloy twin boundaries.
- Xiaojun Zhao
- , Houwen Chen
- & Jian-Feng Nie
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Article
| Open AccessDendrite fragmentation induced by massive-like δ–γ transformation in Fe–C alloys
Transitioning from columnar to equiaxed grains is paramount for desired microstructures during steel casting. Here, the authors report a new fragmentation mechanism based on a phase transition at grain boundaries that can contribute to equiaxed grains.
- Hideyuki Yasuda
- , Kohei Morishita
- & Akihisa Takeuchi
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Article
| Open AccessPore elimination mechanisms during 3D printing of metals
3D printing pore-free complex metal parts remains a challenge. Here, the authors combine in-situ imaging and simulations to show thermocapillary force can eliminate pores from the melt pool during a laser powder bed fusion process.
- S. Mohammad H. Hojjatzadeh
- , Niranjan D. Parab
- & Lianyi Chen
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Article
| Open AccessIn-operando high-speed microscopy and thermometry of reaction propagation and sintering in a nanocomposite
Imaging highly exothermic reactions in high spatial and temporal resolution to understand their underlying reaction mechanisms is challenging. Here, the authors develop a high-speed microscopy/pyrometry imaging system to successfully observe reactive sintering in a nanothermite reaction in-operando.
- Haiyang Wang
- , Dylan J. Kline
- & Michael R. Zachariah