Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Heterogeneous lamella structure unites ultrafine-grain strength with coarse-grain ductility.

ABSTRACT: Grain refinement can make conventional metals several times stronger, but this comes at dramatic loss of ductility. Here we report a heterogeneous lamella structure in Ti produced by asymmetric rolling and partial recrystallization that can produce an unprecedented property combination: as strong as ultrafine-grained metal and at the same time as ductile as conventional coarse-grained metal. It also has higher strain hardening than coarse-grained Ti, which was hitherto believed impossible. The heterogeneous lamella structure is characterized with soft micrograined lamellae embedded in hard ultrafine-grained lamella matrix. The unusual high strength is obtained with the assistance of high back stress developed from heterogeneous yielding, whereas the high ductility is attributed to back-stress hardening and dislocation hardening. The process discovered here is amenable to large-scale industrial production at low cost, and might be applicable to other metal systems.

SUBMITTER: Wu X

PROVIDER: S-EPMC4664339 | biostudies-other | 2015 Nov

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Similar Datasets

Nanodomained Nickel Unite Nanocrystal Strength with Coarse-Grain Ductility.

Project description:Conventional metals are routinely hardened by grain refinement or by cold working with the expense of their ductility. Recent nanostructuring strategies have attempted to evade this strength versus ductility trade-off, but the paradox persists. It has never been possible to combine the strength reachable in nanocrystalline metals with the large uniform tensile elongation characteristic of coarse-grained metals. Here a defect engineering strategy on the nanoscale is architected to approach this ultimate combination. For Nickel, spread-out nanoscale domains (average 7?nm in diameter) were produced during electrodeposition, occupying only ~2.4% of the total volume. Yet the resulting Ni achieves a yield strength approaching 1.3?GPa, on par with the strength for nanocrystalline Ni with uniform grains. Simultaneously, the material exhibits a uniform elongation as large as ~30%, at the same level of ductile face-centered-cubic metals. Electron microscopy observations and molecular dynamics simulations demonstrate that the nanoscale domains effectively block dislocations, akin to the role of precipitates for Orowan hardening. In the meantime, the abundant domain boundaries provide dislocation sources and trapping sites of running dislocations for dislocation multiplication, and the ample space in the grain interior allows dislocation storage; a pronounced strain-hardening rate is therefore sustained to enable large uniform elongation.

| S-EPMC4485168 | biostudies-literature

Dynamically reinforced heterogeneous grain structure prolongs ductility in a medium-entropy alloy with gigapascal yield strength.

Project description:Ductility, i.e., uniform strain achievable in uniaxial tension, diminishes for materials with very high yield strength. Even for the CrCoNi medium-entropy alloy (MEA), which has a simple face-centered cubic (FCC) structure that would bode well for high ductility, the fine grains processed to achieve gigapascal strength exhaust the strain hardening ability such that, after yielding, the uniform tensile strain is as low as ∼2%. Here we purposely deploy, in this MEA, a three-level heterogeneous grain structure (HGS) with grain sizes spanning the nanometer to micrometer range, imparting a high yield strength well in excess of 1 GPa. This heterogeneity results from this alloy's low stacking fault energy, which facilitates corner twins in recrystallization and stores deformation twins and stacking faults during tensile straining. After yielding, the elastoplastic transition through load transfer and strain partitioning among grains of different sizes leads to an upturn of the strain hardening rate, and, upon further tensile straining at room temperature, corner twins evolve into nanograins. This dynamically reinforced HGS leads to a sustainable strain hardening rate, a record-wide hysteresis loop in load-unload-reload stress-strain curve and hence high back stresses, and, consequently, a uniform tensile strain of 22%. As such, this HGS achieves, in a single-phase FCC alloy, a strength-ductility combination that would normally require heterogeneous microstructures such as in dual-phase steels.

| S-EPMC6048477 | biostudies-literature

Enhanced strength-ductility synergy in ultrafine-grained eutectic high-entropy alloys by inheriting microstructural lamellae.

Project description:Realizing improved strength-ductility synergy in eutectic alloys acting as in situ composite materials remains a challenge in conventional eutectic systems, which is why eutectic high-entropy alloys (EHEAs), a newly-emerging multi-principal-element eutectic category, may offer wider in situ composite possibilities. Here, we use an AlCoCrFeNi2.1 EHEA to engineer an ultrafine-grained duplex microstructure that deliberately inherits its composite lamellar nature by tailored thermo-mechanical processing to achieve property combinations which are not accessible to previously-reported reinforcement methodologies. The as-prepared samples exhibit hierarchically-structural heterogeneity due to phase decomposition, and the improved mechanical response during deformation is attributed to both a two-hierarchical constraint effect and a self-generated microcrack-arresting mechanism. This work provides a pathway for strengthening eutectic alloys and widens the design toolbox for high-performance materials based upon EHEAs.

| S-EPMC6353877 | biostudies-literature

Segregation mediated heterogeneous structure in a metastable β titanium alloy with a superior combination of strength and ductility.

Project description:In β titanium alloys, the β stabilizers segregate easily and considerable effort has been devoted to alleviate/eliminate the segregation. In this work, instead of addressing the segregation problems, the segregation was utilized to develop a novel microstructure consisting of a nanometre-grained duplex (α+β) structure and micrometre scale β phase with superior mechanical properties. An as-cast Ti-9Mo-6W alloy exhibited segregation of Mo and W at the tens of micrometre scale. This was subjected to cold rolling and flash annealing at 820 oC for 2 and 5 mins. The solidification segregation of Mo and W leads to a locally different microstructure after cold rolling (i.e., nanostructured β phase in the regions rich in Mo and W and plate-like martensite and β phase in regions relatively poor in Mo and W), which play a decisive role in the formation of the heterogeneous microstructure. Tensile tests showed that this alloy exhibited a superior combination of high yield strength (692 MPa), high tensile strength (1115 MPa), high work hardening rate and large uniform elongation (33.5%). More importantly, the new technique proposed in this work could be potentially applicable to other alloy systems with segregation problems.

| S-EPMC5951864 | biostudies-literature

Microalloying ultrafine grained Al alloys with enhanced ductility.

Project description:Bulk ultrafine grained (UFG)/nanocrystal metals possess exceptional strength but normally poor ductility and thermal stability, which hinder their practical applications especially in high-temperature environments. Through microalloying strategy that enables the control of grains and precipitations in nanostructured regime, here we design and successfully produce a highly microstructure-stable UFG Al-Cu-Sc alloy with ~275% increment in ductility and simultaneously ~50% enhancement in yield strength compared with its Sc-free counterpart. Although the precipitations in UFG alloys are usually preferentially occurred at grain boundaries even at room temperature, minor Sc addition into the UFG Al-Cu alloys is found to effectively stabilize the as-processed microstructure, strongly suppress the ?-Al2Cu phase precipitation at grain boundary, and remarkably promote the ?'-Al2Cu nanoparticles dispersed in the grain interior in artificial aging. A similar microalloying strategy is expected to be equally effective for other UFG heat-treatable alloys.

| S-EPMC3884224 | biostudies-literature

Primary human epithelial cells exposed to coarse, fine and ultrafine particles

Project description:The purpose of this study was to characterize global gene expression in human airway epithelial cells and identify cellular pathways associated with coarse, fine and ultrafine particulate matter (PM) exposures. Ambient PM was collected in 3 different size fractions from Chapel Hill air, particles were extracted from foam or filter matrices and lyophilized. Human primary airway epithelial cells were exposed to particles at 250μg/ml or vehicle control for 6h in culture. Following exposure, RNA was isolated and hybridized to human HG U133A affymetrix chips. Keywords: particle treatment

2008-05-01 | GSE7010 | GEO

Tribological Behavior of the 316L Stainless Steel with Heterogeneous Lamella Structure.

Project description:In this paper, the tribological behavior of 316L stainless steel with heterogeneous lamella structure (HLS), prepared through 85% cold rolling technology and subsequent annealing treatment (750 °C, 10 min), were conducted on a ball-on-disc tribometer under different normal loads in dry ambient air conditions. The morphologies, structures, and compositions of the raw and worn surfaces were analyzed by 3D surface profilometer, XRD, SEM, EDS and TEM. Based on this, the results showed that the HLS 316L stainless steel samples exhibited lower and more steady friction coefficients than coarse-grained samples, especially under higher loads, which can be attributed to the existence of numerous oxidative particles across sliding interfaces. However, the wear resistance of HLS 316L stainless steel sample was a little weakened compared to that of the coarse-grained sample under a normal load of 5 N. When the load increases up to 15 N, an obviously decreased wear resistance was found for the HLS of the 316L stainless steel sample, which was 50% lower than that of coarse-grained sample. This can be ascribed to the more severe oxidative and abrasive wear performance of HLS 316L stainless steel sample under dry sliding conditions.

| S-EPMC6213424 | biostudies-other

Dual heterogeneous structures lead to ultrahigh strength and uniform ductility in a Co-Cr-Ni medium-entropy alloy.

Project description:Alloys with ultra-high strength and sufficient ductility are highly desired for modern engineering applications but difficult to develop. Here we report that, by a careful controlling alloy composition, thermomechanical process, and microstructural feature, a Co-Cr-Ni-based medium-entropy alloy (MEA) with a dual heterogeneous structure of both matrix and precipitates can be designed to provide an ultra-high tensile strength of 2.2 GPa and uniform elongation of 13% at ambient temperature, properties that are much improved over their counterparts without the heterogeneous structure. Electron microscopy characterizations reveal that the dual heterogeneous structures are composed of a heterogeneous matrix with both coarse grains (10∼30 μm) and ultra-fine grains (0.5∼2 μm), together with heterogeneous L12-structured nanoprecipitates ranging from several to hundreds of nanometers. The heterogeneous L12 nanoprecipitates are fully coherent with the matrix, minimizing the elastic misfit strain of interfaces, relieving the stress concentration during deformation, and playing an active role in enhanced ductility.

| S-EPMC7220923 | biostudies-literature

Predicting RNA 3D structure using a coarse-grain helix-centered model.

Project description:A 3D model of RNA structure can provide information about its function and regulation that is not possible with just the sequence or secondary structure. Current models suffer from low accuracy and long running times and either neglect or presume knowledge of the long-range interactions which stabilize the tertiary structure. Our coarse-grained, helix-based, tertiary structure model operates with only a few degrees of freedom compared with all-atom models while preserving the ability to sample tertiary structures given a secondary structure. It strikes a balance between the precision of an all-atom tertiary structure model and the simplicity and effectiveness of a secondary structure representation. It provides a simplified tool for exploring global arrangements of helices and loops within RNA structures. We provide an example of a novel energy function relying only on the positions of stems and loops. We show that coupling our model to this energy function produces predictions as good as or better than the current state of the art tools. We propose that given the wide range of conformational space that needs to be explored, a coarse-grain approach can explore more conformations in less iterations than an all-atom model coupled to a fine-grain energy function. Finally, we emphasize the overarching theme of providing an ensemble of predicted structures, something which our tool excels at, rather than providing a handful of the lowest energy structures.

| S-EPMC4436664 | biostudies-literature

Change of Deformation Mechanisms Leading to High Strength and Large Ductility in Mg-Zn-Zr-Ca Alloy with Fully Recrystallized Ultrafine Grained Microstructures.

Project description:Recently, we have found that fully recrystallized ultrafine-grained (UFG) microstructures could be realized in a commercial precipitation-hardened Magnesium (Mg) alloy. The UFG specimens exhibited high strength and large ductility under tensile test, but underlying mechanisms for good mechanical properties remained unclear. In this study, we have carried out systematic observations of deformation microstructures for revealing the influence of grain size on the change of dominant deformation modes. We found that plastic deformation of conventionally coarse-grained specimen was predominated by {0001} <11-20> slip and {10-12} <10-11> twinning, and the quick decrease of work-hardening rate was mainly due to the early saturation of deformation twins. For the UFG specimens, {10-12} <10-11> twinning was dramatically suppressed, while non-basal slip systems containing <c> component of Burgers vector were activated, which contributed significantly to the enhanced work-hardening rate leading to high strength and large ductility. It was clarified by this study that limited ductility of hexagonal Mg alloys could be overcome by activating unusual slip systems (<c + a> dislocations) in fully recrystallized UFG microstructures.

| S-EPMC6691010 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data