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Robert Ritchie   (Source: Roy Kaltschmidt, Berkeley Lab Public Affairs)
This damage-tolerant metallic glass is made of microalloys of palladium with phosphorous, germanium, silicon and silver

Researchers at the California Institute of Technology and the U.S. Department of Energy's (DOE) Lawrence Berkeley National Laboratory have combined efforts to create a glass that is said to be the strongest out of any known material. 

Robert Ritchie, study leader and a material scientist from the Lawrence Berkeley National Laboratory, along with co-authors Marios Demetriou, Glenn Garrett, Joseph Schramm, Maximilien Launey, Douglas Hofmann, and William Johnson of the California Institute of Technology, have developed a glass that is tougher and stronger than steel.

Glassy materials have a non-crystalline, amorphous structure, which makes them strong yet brittle. This type of structure allows cracks and strains to spread throughout the material because the glass' amorphous structure cannot stop crack propagation. To remedy this, the Lawrence Berkeley/California Tech team designed what they called "DH3," which was a fabricated metallic glass capable of preventing cracks from spreading through the use of a second crystalline phase of the metal. While this method prevented the spread of cracks, these researchers wanted to take this research to the next level and make it stronger. 

The Lawrence Berkeley/California Tech team came together once again to develop this new glass, which is a damage-tolerant metallic glass made of microalloys of palladium, which has a high bulk-to-shear stiffness ratio. The difference between this new glass and DH3 is that their new creation also promotes extensive plasticity "through the formation of multiple shear bands before the bands turn into cracks." 

"These results mark the first use of a new strategy for metallic glass fabrication and we believe we can use it to make glass that will be even stronger and more tough," said Ritchie. "Because of the high bulk-to-shear modulus ratio of palladium-containing material, the energy needed to form shear bands is much lower than the energy required to turn these shear bands into cracks. The result is that glass undergoes extensive plasticity in response to stress, allowing it to bend rather than crack."

Ritchie added that it is important to make a metallic glass with at least five elements in order to quench the material, which means to cool the material. The first samples of the metallic glass consisted of microalloys of palladium with phosphorous, germanium, silicon and silver. This increases the thickness of the glass rods, but the size is limited to its need to rapidly quench the liquid metals for its final structure. When it comes time to quench the liquid metals, it doesn't know which crystal structure to form, so it automatically forms an amorphous structure. 

"Our game now is to try and extend this approach of inducing extensive plasticity prior to fracture to other metallic glasses through changes in composition," said Ritchie. "The addition of the palladium provides our amorphous material with an unusual capacity for extensive plastic shielding ahead of an open crack. This promotes a fracture toughness comparable to those of the toughest materials known. The rare combination of toughness and strength, or damage tolerance, extends beyond the benchmark ranges established by the toughest and strongest materials known." 

This study was published in Nature Materials.



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I can't believe it
By torpor on 1/11/2011 2:38:24 PM , Rating: 5
How can there be no aluminum in there?




RE: I can't believe it
By Smartless on 1/11/2011 2:45:52 PM , Rating: 2
Scottie obviously refined the process to use cheaper metals. Hmm better check to see if a few humpback whales can't be accounted for.

Wow if they do refine high tensile glass, that could revolutionize the construction industry. Though I wonder how it performs against materials like Plexiglass.


RE: I can't believe it
By quiksilvr on 1/11/2011 2:56:22 PM , Rating: 2
Weight is another issue as well. If this stuff is heavier than glass, it's already doomed in the automotive industry (although it might have hope in the airplane industry)


RE: I can't believe it
By DanNeely on 1/11/2011 3:11:05 PM , Rating: 2
The aviation industry is even more sensitive to weight than the general automotive industry; race cars are comparable.


RE: I can't believe it
By quiksilvr on 1/11/2011 3:17:31 PM , Rating: 2
Not for the cockpit. Metallic glass would be perfect for that. No more cracks from bird impacts.


RE: I can't believe it
By MGSsancho on 1/11/2011 5:05:35 PM , Rating: 2
the structure is that of a glass, the article says nothing about the new material allowing any light though


RE: I can't believe it
By Jeffk464 on 1/12/2011 7:44:14 PM , Rating: 2
thats what I was thinking, aka volcanic glass.


RE: I can't believe it
By nafhan on 1/11/2011 2:59:23 PM , Rating: 2
Glass isn't necessarily clear. Not sure about this specifically, though.


RE: I can't believe it
By Solandri on 1/11/2011 4:28:45 PM , Rating: 3
Yeah, "glass" in this context is referring to the material's microstructure, not "something you can see through". Metals and alloys normally form microgranules of crystals all glommed together. Most of the material properties we associate with metals are a consequence of this. e.g. bending is microcrystals sliding against each other while staying glommed together. Work hardening is microcrystals sliding until two discontinuities match up, then latching onto each other to form larger crystals which are stronger but more prone to fracture.

"Glass" refers to a solid whose molecules haven't formed crystals (and are thus amorphous). They're usually optically transparent or translucent, but not always.


RE: I can't believe it
By Randomblame on 1/11/2011 3:00:33 PM , Rating: 5
*talking into his mouse* Hello computer


RE: I can't believe it
By therealnickdanger on 1/11/2011 4:15:01 PM , Rating: 5
The keyboard. How quaint.


RE: I can't believe it
By Astral Abyss on 1/11/2011 2:48:13 PM , Rating: 2
They're still trying to figure that out.


RE: I can't believe it
By strikeback03 on 1/11/2011 3:13:15 PM , Rating: 2
That would be this stuff: http://en.wikipedia.org/wiki/Aluminium_oxynitride

The CEO of a company involved in making this gave a seminar on our campus a few years ago. He had videos of it under testing to be used as outer domes for sensors that have to see out of aircraft, the test projectiles shatter instead of the alon. Despite this he managed to go the whole seminar without a single transparent aluminum reference.


RE: I can't believe it
By Exodite on 1/11/2011 3:18:39 PM , Rating: 3
Strictly speaking we've had 'transparent aluminum' around for quite some time already.

Good old sapphire glass, aka the synthetic sapphire that you see in high-end wrist-watches and the like, is an aluminum oxide.


RE: I can't believe it
By walk2k on 1/11/2011 3:22:55 PM , Rating: 2
Is it me or does that guy look WAY too much like Scotty??


RE: I can't believe it
By magreen on 1/11/2011 3:39:12 PM , Rating: 2
Maybe he's Scotty's great-great-grandfather.


RE: I can't believe it
By Lazarus Dark on 1/12/2011 8:20:51 AM , Rating: 2
seriously, just picture gray/white hair and boom!: Scotty


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