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Wednesday, 5 November 2014

Metallic Glass hits the golf ball further and is likely to hit the global market just as hard!

"Throw a rock through a window made of silica glass, and the brittle, insulating oxide pane shatters. But whack a golf ball with a club made of metallic glass—a resilient conductor that looks like metal—and the glass not only stays intact but also may drive the ball farther than conventional clubs. In light of this contrast, the nature of glass seems anything but clear." ref., Phys.org.,newsletter, 0ct.2 014-10-18.



"A new study at the Department of Energy's Oak Ridge National Laboratory, published Sept. 24 in Nature Communications, has cracked one mystery of glass to shed light on the mechanism that triggers its deformation before shattering. The study improves understanding of glassy deformation and may accelerate broader application of metallic glass, a moldable, wear-resistant, magnetically exploitable material that is thrice as strong as the mightiest steel and ten times as springy.
Whereas metals are usually crystalline, metallic glasses are amorphous in atomic structure. Amorphous metals, studied since the 1950s, have a tendency to crystallise when heated, which makes them extremely brittle. Metallic glass alloys that did not crystallise so easily were discovered at Tohoku University and Caltech in 1991 and introduced commercially in golf clubs in 2001."
How materials deform is still high on the research agenda:
"the researchers calculated how atoms move on a personal computer. To describe deformation at the atomic level, they sampled a large number of paths along which a system can evolve. Analysing the ensuing ensemble, they arrived at the statistically likely scenario."
"We unravelled the mystery of this deformation mechanism in not only the metallic  system but also the general amorphous system," Fan said. "It's a challenging randomness problem, but from this huge model statistical result, we find [these two systems] are surprisingly governed by the same mechanism."
"Next the researchers will explore what happens between deformation and shattering. "As a consequence of deformation, next comes the stage where 20 atoms are affected," Egami said. "Sometimes they start an avalanche. Then hundreds of atoms are involved. At the end, all atoms in the system are involved—billions of atoms. So shattering is first started by five and then snowballs into big action."
The researchers' improved fundamental understanding of  creates new knowledge of a material class about which little is known. Such advances may contribute to the USA, federal government's Materials Genome Initiative, launched in 2011 to accelerate discovery, manufacture and deployment of advanced materials for the global marketplace.
Metallurgist and Golfers alike maybe pleased to read more on the topic of Metallic Glasses via links provided by Phys.org.,  and in particular,  Nature Communications. 

Read more at Phys.org 


Three cheers to the metallurgical & mat sci community. Golfers Enjoy.
Original Article Title:

Atomic trigger shatters mystery of how glass deforms:



'via Blog this'

Thursday, 23 October 2014

NOBEL PRIZE AWARDS 2014-blog up dates and links

A longstanding, if not awaited, up-date of my pages was badly needed. This has been done. Unfortunately for me, I was unable to continue using Nobel.org, RSS Feed to capture the information as had been the case up to 2012. This appears to have been abandoned by Nobel.org. Much more effort was required by me, but is now complete. Readers will see the three prizes most relevant to Materials Scientists and Engineers namely: PhysicsChemistry and Economic Sciences. This is in no way an under estimation of two fundamental subjects of huge significance for all humanity and rightly given prominence by Albert Nobel's far-sighted Awards: Peace and Medicine.

Looking forward to reading the Prize Winners Lectures usually available towards the end of 2014.

Comments welcome.

Wednesday, 15 October 2014

Surprising behaviour of metallic nanoparticles, "They wobble jelly like!"

The following report was brought to my  notice  by The Institute of Physics,UK (IOP) outreach team "Physics in Society"at the IOP. ( Phys.org Newsletter, Oct. 12, 2014).  A short summary follows:

A surprising phenomenon has been found in metal nanoparticles: They appear, from the outside, to be liquid droplets, wobbling and readily changing shape, while their interiors retain a perfectly stable crystal configuration. 

The results, published in the journal Nature Materials, come from a combination of laboratory analysis and computer modeling, by an international team that included researchers in China, Japan, and Pittsburgh, as well as at MIT.

                                          Credit: Yan Liang

More info & images may be found in NATURE MATERIALS | LETTER "Liquid-like pseudoelasticity of sub-10-nm crystalline ​silver particles" ,

  • Jun Sun,
  • Longbing He,
  • Yu-Chieh Lo,
  • Tao Xu,
  • Hengchang Bi,
  • Litao Sun,
  • Ze Zhang,
  • Scott X. Mao
  • Ju Li
  • Received 
    Accepted 
    Published online
    12 October 2014.

    The experiments were conducted at room temperature, with particles of pure silver less than 10 nanometers across—less than one-thousandth of the width of a human hair. But the results should apply to many different metals, says Li, senior author of the paper and the BEA Professor of Nuclear Science and Engineering.
    Silver has a relatively high melting point—962 degrees Celsius, or 1763 degrees Fahrenheit—so observation of any liquidlike behavior in its nanoparticles was "quite unexpected," Li says. Hints of the new phenomenon had been seen in earlier work with tin, which has a much lower melting point, he says.

    The use of nanoparticles in applications ranging from electronics to pharmaceuticals is a lively area of research; generally, Li says, these researchers "want to form shapes, and they want these shapes to be stable, in many cases over a period of years." So the discovery of these deformations reveals a potentially serious barrier to many such applications: For example, if gold or silver nanoligaments are used in electronic circuits, these deformations could quickly cause electrical connections to fail.

    The researchers' detailed imaging with a  and atomistic modeling revealed that while the exterior of the  appears to move like a liquid, only the outermost layers—one or two atoms thick—actually move at any given time. As these outer layers of atoms move across the surface and redeposit elsewhere, they give the impression of much greater movement—but inside each particle, the atoms stay perfectly lined up, like bricks in a wall.

    "The interior is crystalline, so the only mobile atoms are the first one or two monolayers," Li says. "Everywhere except the first two layers is crystalline."
    By contrast, if the droplets were to melt to a liquid state, the orderliness of the crystal structure would be eliminated entirely
    Technically, the particles' deformation is pseudoelastic, meaning that the material returns to its original shape after the stresses are removed—like a squeezed rubber ball—as opposed to plasticity, as in a deformable lump of clay that retains a new shape.
    The phenomenon of plasticity by interfacial diffusion was first proposed by Robert L. Coble, a professor of ceramic engineering at MIT, and is known as "Coble creep." "What we saw is aptly called Coble pseudoelasticity," Li says.
    Now that the phenomenon has been understood, researchers working on nanocircuits or other nanodevices can quite easily compensate for it, Li says. If the nanoparticles are protected by even a vanishingly thin layer of oxide, the liquid-like behaviour is almost completely eliminated, making stable circuits possible.

    REFS:
    Unexpected finding shows nanoparticles keep their internal crystal structure while flexing like droplets




    Friday, 26 September 2014

    Perhaps one of the most important discoveries in cement science this century.



    Perhaps one of the most important discoveries in cement science this century, say researchers at Rice Univ Texas

    “Green” concrete can lower concrete's CO2 atmospheric contribution

    MORE?
    1. “Green” concrete can lower concrete's CO2 atmospheric contribution

    2. NATURE COMMUNICATIONS  : Combinatorial molecular optimization of cement hydrates (pdf)  Published 24 Sep 2014.

    Monday, 1 September 2014

    GE pins images to fire the imagination of metallurgists and materials scientists-jobs in innovations

    Our version of "spring break" includes pushing super materials to the limit so we can learn how to m... - http://pinterest.com/pin/423338433696990354/?utm_source=android_share

    Saturday, 16 August 2014

    Copper foam turns CO2 into useful chemicals -ref Materials Today





    A catalyst made from a foamy form of copper has vastly different electrochemical properties from catalysts made with smooth copper in reactions involving carbon dioxide, a new study shows. The research, by scientists in Brown University’s Center for the Capture and Conversion of CO2, suggests that copper foams could provide a new way of converting excess CO2 into useful industrial chemicals. For example a photo of Cu foam from ERG Materials and Aerospace is given as follows:






    Example of Copper Properties 


    “Copper has been studied for a long time as an electrocatalyst for CO2 reduction, and it’s the only metal shown to be able to reduce CO2 to useful hydrocarbons,” said Tayhas Palmore, professor of engineering and senior author of the new research. “There was some indication that if you roughen the surface of planar copper, it would create more active sites for reactions with CO2.”




    'As levels of carbon dioxide in the atmosphere continue to rise, researchers are looking for ways to make use of it. One approach is to capture CO2 emitted from power plants and other facilities and use it as a carbon source to make industrial chemicals, most of which are currently made from fossil fuels. The problem is that CO2 is extremely stable, and reducing it to a reactive and useful form isn’t easy.


    Now,copper foam, which has been developed only in the last few years, provided the surface roughness (and increased surface area?-reaction:chemical rate controlled or mass transfer controlled?) for which Palmore and her colleagues were looking. The foams are made by depositing copper on a surface in the presence of hydrogen and a strong electric current. Hydrogen bubbles cause the copper to be deposited in an arrangement of sponge-like pores and channels of varying sizes.'


    'After depositing copper foams on an electrode, the researchers set up experiments to see what kinds of products would be produced in an electrochemical reaction with CO2 in water.'




    The experiments showed that the copper foam converted CO2 into formic acid — a compound often used as a feedstock for microbes that produce biofuels — at a much greater efficiency than planar copper. The reaction also produced small amounts of propylene, a useful hydrocarbon that’s never been reported before in reactions involving copper.
    “The product distribution was unique and very different from what had been reported with planar electrodes, which was a surprise,” Palmore said. “We’ve identified another parameter to consider in the electroreduction of CO2. It’s not just the kind of metal that’s responsible for the direction this chemistry goes, but also the architecture of the catalyst.”
    'Now that it’s clear that architecture matters,  It’s likely, Palmore says, that pores of different depths or diameters will produce different compounds from a CO2 feedstock. Ultimately, it might be possible to tune the copper foam toward a specific desired compound.'


    Copper foam turns CO2 into useful chemicals - Materials Today

    Thursday, 7 August 2014

    Entropy | Free Full-Text | Physical Properties of High Entropy Alloys


    Introduction 

    High entropy alloys (HEAs) are a novel class of metallic material with a distinct design strategy [1,2]. Different from conventional alloys that are typically designed based on one or two principal
    elements, HEAs are composed of more than five principal elements. It has been reported that
    HEAs possess many attractive properties, such as high hardness [3–7], outstanding wear resistance [8,9], good fatigue resistance characteristics [10], excellent high-temperature strength [11,12], good
    thermal stability [13] and, in general, good oxidation [8] and corrosion resistance [14,15]. These
    properties suggest great potential in a wide variety of applications. Thus, HEAs have received
    significant attention in recent years. Up till now, more than 300 HEAs have been developed,
    forming a new frontier of metallic materials. Most studies on HEAs are focused on the
    relationships between phase, microstructure, and mechanical properties. Although less attention
    was paid to the physical properties of HEAs, they are actually also quite encouraging. This paper
    briefly reviews current understanding of the physical properties of HEAs, with emphasis on the
    magnetic, electrical, and thermal properties

    Examples of magnetic properties:


    CLICK to VIEW FULL TABLES

    Electrical & Thermal Conductivity


    Full paper tables,graphs and references at the link below :

    Entropy | Free Full-Text | Physical Properties of High Entropy Alloys

    High Purity Cr sources for Superalloys

    Energy for th Future:Phil.Trans.A-Vol. 365, N° 1853 / April 15, 2007, curtesy The Royal Soc. London

    Engineered foams and porous materials: Phil Trans A. Vol 364, N° 1838 / 06 curtesy_The R Soc. Lond