Nav: Home

Towards better metallic glasses

October 25, 2016

Researchers from the University of Bristol have used state-of-the-art computer simulation to test a theory from the 1950s that when atoms organise themselves into 3D pentagons they supress crystallisation.

The theory by renowned Bristol physicist, Sir Charles Frank, has been a cornerstone of metallic glass development ever since from high-tech aerospace materials to the covers of our mobile phones.

But until now, the mechanism by which these 3D pentagons could stop the formation of crystal nuclei has been unknown. Metallic glasses have the potential to revolutionise many commercial applications - they have many of the advantageous properties of conventional metals but are much tougher and harder.

This is because the systems are disordered - the atoms are frozen into a complex, tangled structure.

This is unlike conventional metals which naturally form well-arranged ordered structures, called crystals.

The faults in crystals are what cause the material to break when it is stressed, and so metallic glasses can be far stronger - they have no faults between crystal grains.

Dr Patrick Royall from the School of Chemistry, who led this research with colleague Dr Jade Taffs, said: "In order to manufacture these amorphous materials we need to find a way to stop them from forming crystals.

"This is challenging - decades of research have resulted in a largest sample just 7cm in size. The key question - what is the most effective way of stopping crystallisation, remains unsolved."

Now, using computer simulation, Drs Taffs and Royall have uncovered the mechanism by which fivefold symmetry (3D pentagons) in liquids inhibits crystallisation.

Dr Taffs said: "When a crystal is in contact with its liquid, the atoms at the surface of each phase cannot satisfy their bonding constraints: they are "neither liquid nor solid".

"This means the material must pay energy due to the lack of satisfied bonds at the interface between crystal and liquid, and this surface energy is much higher in the case of liquids with fivefold symmetry."

Dr Royall added: "Liquids crystallise through the spontaneous creation of small crystals, and this process is extremely dependent on the size of the surface energy of the crystals.

"Because the surface energy is higher when the liquid has fivefold symmetry, nuclei form at a much lower rate. Identifying the mechanism by which crystallisation may be suppressed is an important step in the development of metallic glasses, and may open the door to using metallic glass in applications from vehicles to spacecraft."
-end-


University of Bristol

Related Metallic Glass Articles:

Crossover from 2D metal to 3D Dirac semimetal in metallic PtTe2 films with local Rashba effect
Shuyun Zhou's group from Tsinghua University reported the evolution of the electronic structure of PtTe2 thin films using angle-resolved photoemission spectroscopy.
New data on ultrafast electron photoemission from metallic nanostructures obtained
Metallic nanoparticle ensembles are capable of emitting short bunches of electrons when irradiated by powerful laser pulses of femtosecond (1 fs = 10-15 s) duration.
Penn engineer's 'metallic wood' has the strength of titanium and the density of water
In a new study published in Nature Scientific Reports, researchers at the University of Pennsylvania's School of Engineering and Applied Science, the University of Illinois at Urbana-Champaign, and the University of Cambridge have built a sheet of nickel with nanoscale pores that make it as strong as titanium but four to five times lighter.
New research questions the 'Glass Cliff' and corroborates the persistent 'Glass Ceiling'
Are women more likely to be appointed to leadership positions in crisis situations when companies are struggling with declining profits?
Metallic nanoparticles light up another path towards eco-friendly catalysts
Scientists at Tokyo Technology produced subnano-sized metallic particles that are very effective as catalysts for the oxidation of hydrocarbons.
More Metallic Glass News and Metallic Glass Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...