Metallic Glass Recipe Generation Breakthrough
Australian researchers have created an instruction manual or recipes for making Metallic glass that could help make this wonder metal fulfill its incredible promise.
Metallic glass sounds like an oxymoron doesn’t it? Kinda like a foamy black hole. Glass is generally considered to be delicate and brittle; it’s the epitome of breakable. Metal is none of these. But what makes glass a glass? Primarily, it’s all about the arrangement of atoms. They are not laid out in an ordered structure. This is why it’s called an amorphous solid. Metal on the other hand is non-amorphous..a crystalline solid with an orderly arrangement of atoms forming crystal lattices.
A metallic glass then does not have this orderly arrangement of atoms like every other metal you’ve probably ever seen. It’s an amorphous metal.
This was discovered in 1960 by Caltech in the U.S. It was created by rapidly cooling an alloy of various metals. The rapid cooling is critical because it prevents the atoms from moving into an orderly arrangement and locks it into its glassy amorphous configuration. And when I say rapid I mean rapid. Back then it had to be cooled at the equivalent of a million degrees per second. Because of that requirement they could only make ribbons or wires of metallic glass that had to be small in at least one dimension to support such a cooling rate . Over the years other alloys permitted a much slower cooling like 10,000 degrees or 100 degrees per second. Some alloys even allowed 1 degree per second. This permitted progressively larger samples of metallic glass to be made but is still ultimately a limiting factor.
Making metal amorphous though, changes its properties in incredibly useful ways.
First and foremost, these alloys are amazingly strong and light. Some have been shown to be an astounding 3 times as strong as titanium. Add to that a high elasticity and resistance to scratching, wear, and corrosion and you have a remarkable material on your hands. It’s no wonder it’s been called the most significant discovery in materials science since the discovery of plastics half a century ago. If the Movie The Graduate is ever remade, perhaps it would change it’s iconic line from..”One word: Plastics” to…”Two words: Metallic Glass”.
Its mechanical properties are only part of its yumminess. Creating products with it could offer tremendous benefits compared to the way regular metals are manipulated. Machining conventional metal using modern methods can be very expensive and wasteful. Metallic glasses on the other hand have been shown to be much easier to manipulate. That’s because it become a viscous deformable solid at certain (supercooled) temperatures. That means between the glass transition and crystallization temperature. This offers many advantages over the classic melt-casting techniques we’ve all seen videos of.
- Casting defects are reduced
- Mold tools suffer less damage due to lower temperatures
- Greater control of geometry and tolerances are also allowed
This means that metallic glass industry has the potential to be quite viable commercially and much more efficient than much of conventional metal working. William L. Johnson, Professor of Materials Science at California Institute of Technology says that it could even become a “disruptive technology in the metals industry”
I love disruptive technologies.
As usual, cool new technologies develop far too slowly for my tastes. This may be about to change. Researchers in Sydney have come up with a novel model of the atomic structure of metallic glass. This allows them to predict which combination of metals have the potential to become metallic glass. This could be a tremendous benefit since metallic glass is often made of varying percentages of multiple metals like lanthanum, magnesium, zirconium, palladium, iron, copper, and titanium. The combinations and permutations of these metals and others is so high that laboratory testing is a very slow, hit-or-miss affair.
Based on this model, the scientists have already been able to successfully predict no fewer than 200 new metallic glass alloys just based on titanium, magnesium, silver, copper, and zinc.
Of course, there are still hurdles to be overcome before metallic glass can reach its full potential. One is that it is often seen to age quickly. Exposure to constant stresses can sometimes make it prematurely and unexpectedly brittle. This too may be a thing of the past however. Chinese researchers at the Institute of Physics in Beijing recently found an interesting solution to this problem by giving the glass a cryogenic bath. They dip it into a super-low temperature liquid and let it cool back to room temperature about a dozen times. The scientists contend that the premature aging is caused by the random arrangement of atoms in the amorphous solid not being random enough (what they call the “intrinsic non-uniformity of the glass structure”). Essentially there are some orderly structures here and there throughout the material. They claim the cryo-bath makes the the metallic glass even more random decreasing the material’s internal stability. The result is what they call a “game-changing ” ultimate solid.
The applications, as you may imagine are pretty extensive. Such a metal in widespread production would dramatically change the space race where weight and strength are king. Spacecraft body construction and space debris shields are the obvious low-hanging fruit. Chinese researchers compare this to turning a spacecraft from the trucks they are today to the equivalent of race cars. Space vehicles aren’t the only space applications. This can also be used for structures on the Moon or Mars.
Other potential applications include:.
- Hydrogen storage materials in next generation batteries (if the hydrogen economy ever materializes).
- Armour-piercing projectiles that can pierce bulletproof vests or even tanks.
- Personal electronic devices that contain incredibly strong components and have their frames and casings made of metallic glass
Many medical applications are also likely as well. The one that caught my attention is a metallic glass that has been created from titanium, paladium, copper, and zirconium. It’s non-carcinogenic (which is always nice) plus it has high wear resistance and won’t undergo shrinkage on solidification. The stand-out attributes though are a strength three times that of titanium and an elastic modulus comparable to bones. They’ve even worked out a way to attach it directly to bones using lasers.
Check…I am now potentially one step closer to being Wolverine (except I can’t grow cool sideburns)
Image Credit: http://phys.org/news/2013-06-window-glasses.html