Sentences with phrase «grain boundaries»

Within each grain, the atoms are neatly arranged, but at grain boundaries, the pattern is disrupted.

These fractures were not along grain boundaries or other surfaces of weakness, as one would expect.

Researchers said their paper is the first to attempt to crack the code of the atomic structures that heavily influence grain boundary properties with the computer algorithms of machine learning.

More importantly, grain boundaries help determine the properties of metals important to humans.

Atomistic models and atomic - resolution STEM HAADF (scanning transmission electron microscopic high - angle annular dark - field) images showing three examples of segregation - induced superstructures observed at randomly - selected general grain boundaries of a nickel - bismuth (Ni - Bi) polycrystalline alloy.

By annealing the films to create larger grains, they could change the types and distribution of grain boundaries at the surface.

They created a micron - sized, individual graphene grain boundary in order to probe its electronic properties and study its role in gas sensing.

The linear elasticity model is then used to study the effects of lattice symmetry, mass density distribution and grain boundaries on the vibrational band structures.

Zhu, along with collaborators at Lawrence Livermore National Laboratory, developed a computational tool based on evolutionary algorithms that performs efficient grand - canonical grain boundary structure search.

Bulk defects in a metal, such as grain boundaries, can create regions of increased strain at its surface that could affect its catalytic activity.

Presumably, the web structures are grain boundaries between crystalline solid lipid.

The discovery of ordered, segregation - induced superstructures at general grain boundaries challenges a traditional view in physical metallurgy

Grain boundaries create strained regions in polycrystalline materials by stabilizing dislocations and may provide a way to create high - energy surfaces for catalysis that are kinetically trapped.

This basic science provided key insights into the microstructure and microchemistry controlling grain boundary sliding.

We have a large database, and our algorithm is taking grain boundaries and comparing it against that database to connect them to certain properties.»

Prior studies of atomic - level grain boundary and segregation structures have been mostly focused on small - angle or special symmetrical tilt and twist boundaries with high symmetries and well - defined periodicities in artificial bicrystals.

BYU researchers said this paper is the first to attempt to crack the code of the atomic structures that heavily influence grain boundary properties with the computer algorithms of machine learning.

It may not be as catchy as chains and weak links, but physicists and engineers know «a material is only as strong as its weakest grain boundary.»

«Breaking down metal oxide into tiny particles increases its surface area and exposes lots of ultra-small, interconnected grain boundaries that become active sites for the water - splitting catalytic reaction,» Cui said.

To develop the memtransistor, Hersam's team again used atomically thin MoS2 with well - defined grain boundaries, which influence the flow of current.

In fields like metallurgy, defects are removed «by turning up the temperature to give molecules more freedom to move grain boundaries and voids,» she said.

Using this technique, investigators have crystallized small molecules (predominantly water) to organize colloid particles, but, due to the intrinsic kinetics of these processes, the particles are normally expelled into the microscale grain boundaries, and so researchers have not been able to order nanoparticles across the multiple scales necessary to mimic nacre.

«The active component in a laser is a single crystal,» said Lograsso, who is also an Iowa State University adjunct professor of materials science and engineering, «because the crystal grain boundaries would scatter the light.»

«In the semiconductor industry, for example, large single crystals of silicon are used to produce microchips, to avoid grain boundaries that otherwise alter the local electronic properties and degrade the performance of transistors in these devices.»

The scientists examined grain boundary sliding and superplastic deformation.

Meanwhile, for grain boundary oxidation, the model can account for the penetration velocity, penetration depth, and depletion distance ahead of the advancing oxidation front based on the competition of oxidation and transport properties of various species.

The calculations showed how various defects and grain boundaries arise as different combinations of sumanenes and corannulenes fuse at different temperatures and over different periods of time.

HP: Radiation damage in a mineral distorts and expands its lattice structure, just as well - organized, tightly - stacked blocks take up more space after someone suddenly shakes them.77 Ramdohr explained how a slow expansion over many years would produce fractures along only grain boundaries and planes of weakness, but a sudden, explosive expansion would produce the fractures he observed.

«The problem of understanding defects in organic electronic materials including grain boundaries is very important for any device application,» Rivnay said.

Researchers observed and investigated segregation - induced superstructures at randomly - selected general grain boundaries of a Ni - Bi polycrystalline alloy via aberration - corrected scanning transmission electron microscopy (AC STEM), in conjunction with first - principles density functional theory calculations.

Grain boundaries in p - n junction diodes fabricated in laser - recrystallized silicon thin films

Moreover, we studied how vacancies and adding new atoms to the structure can affect this lattice thermal conductivity and, finally, we propose the use of grain boundaries as a strategy to reduce this conductivity, according to our analysis on this field.

For selected RE-intermetallics (e.g. of the ThMn12 - structure type) the impacts of atomic rearrangements at surfaces and grain boundaries on the local magnetic properties are presented.

In contrast, the new research suggests that once those isolated pores grow large enough to connect, the molten metal starts to flow, and most of it is able to percolate along grain boundaries.

The segregation of alloying elements or impurities at grain boundaries can significantly alter, often severely degrade, the mechanical and physical properties of engineered alloys.

Although grain - boundary density has previously been correlated with catalytic activity for some reactions, direct evidence that grain boundaries create surfaces with enhanced activity is lacking.

Conventional metals dent, tear, and rust because of defects known as grain boundaries and dislocations, in which the crystals are pushed out of alignment and provide entry points for oxidation.

A team of researchers found that randomly selected, high - angle, general grain boundaries in a nickel - bismuth (Ni - Bi) polycrystalline alloy can undergo interfacial reconstruction to form ordered superstructures, a discovery that enriches the theories and fundamental understandings of both grain boundary segregation and liquid metal embrittlement in physical metallurgy.

More specifically, interfacial reconstructions that change the 2 - D translational symmetries, which are known to occur frequently at crystalline surfaces, were thought impossible to be realized at general grain boundaries that should be lacking long - range translational symmetries.

But researchers showed that it is enabled by faceting, as well as the formation of atomic - level steps at the grain boundaries, which allows separate interfacial reconstructions to occur at both terminating grain surface planes in a unique «bilayer» interfacial phase (wherein an «interfacial phase» refers to a thermodynamically 2 - D phase spontaneously - formed at an interface, which is also called a «complexion»).

Researchers believe that these new and somewhat surprising discoveries are scientifically important and enrich our fundamental understanding of the general grain boundaries that often control the performance properties of various polycrystalline engineered materials.

«Segregation - induced ordered superstructures at general grain boundaries in a Ni - Bi alloy: The discovery of ordered, segregation - induced superstructures at general grain boundaries challenges a traditional view in physical metallurgy.»

However, most grain boundaries in polycrystalline materials are so - called «general» grain boundaries of mixed tilt and twist character, which are not well understood due to the difficulties in characterizing and modeling them.

OK, that's not catchy at all, but here's the point: grain boundaries are a big deal.

This discovery shows that segregation - induced ordered superstructures are not limited to special grain boundaries that are inherently periodic, but may exist at a variety of general grain boundaries that were thought to be lacking any long - range order; hence, they can affect the performance of polycrystalline engineering alloys.

Yet, such general grain boundaries are often significantly weaker mechanically and chemically than the well - studied special grain boundaries, thereby limiting properties and performance of engineered materials.

But while researchers have studied grain boundaries for decades and gained some insight into the types of properties grain boundaries produce, no one has been able to nail down a universal system to predict if a certain configuration of atoms at grain boundaries will make a material stronger or more pliable.