Posting in Technology
Researchers have made a metallic glass that is the strongest and toughest material ever made.
The Golden Gate bridge is made out of a relatively low strength steel, so it won't break when an earthquake rattles the Bay Area.
When you have a structure, you tend not to use the higher strength one. As you increase strength, you decrease the toughness.
A tough material is less likely to fracture. The stronger a material is, the more likely the structure will break.
That is the problem. You can't win because you want the material to be both things!
But researchers at the University of California at Berkeley and California Institute of Technology have created a metallic glass that can get around that problem. The new metallic glass is stronger and tougher than steel (and any other material known to man).
Robert Ritchie, a Berkeley materials scientist, said "trying to get high strength and high toughness is very difficult. One of the holy grails is to get both high strength and high toughness [in materials]. We call that damage tolerance."
To make this metallic glass, the researchers used five elements to confuse the material. That way, the material couldn't flex into automatic memory and form its normal, crystal structure.
This is unusual, considering all metals have crystalline structures. Window panes are amorphous and aren't crystalline in structure.
Like glass, the fabricated material was not crystalline.
"We learned to make metals in this amorphous state," Ritchie said. "There are stronger materials and there may be tougher materials, we know of no other material with the combination [we've made]. Strength and toughness are mutually exclusive, and we've achieved it in a material that you wouldn't expect - in glass. Glass is usually brittle," Ritchie said.
The group from Cal Tech made the material from five or more elements. They melted it and it cooled quickly. The material wasn't able to crystallize, so it formed an amorphous material. The Cal Tech team cut the material into little rods and sent them to Ritchie's team at Berkeley to basically destroy the metallic glass.
The experiments didn't involve throwing the metallic glass against the floor though. Instead, Ritchie ran the metallic glass through mechanical testing machines. The machines could barely make the material crack.
In the future, the new material could be used in nuclear pressure vessels because it has the same toughness as the material used today. A better material could help nuclear reactors avoid a catastrophic failure.
Let's remember that the new material was born out of academic curiosity. People have been fascinated with ways of finding materials that have both strength and toughness. Ritchie seems to have actually made a material that lives up to the dream.
It will be interesting to see how this material will be used in the future.
Photo: Max Launey
Jan 11, 2011
Also, the five alloying elements most often mentioned for "work hardenable ductile bulk metallic glass" (and their spot price as metallurgically pure stuffs) are: --(Zr) Zirconium ($250/kg) --(Ti) Titanium ($26/kg) --(Ni) Nickel ($29/kg) --(Cu) Copper ($10/kg) --(Be) Beryllium ($500/kg) (Note that beryllium-containing alloys are typically redflagged as inhalation hazards and can cause anaphylactic shock in some individuals) Some alloys also include --(Pt) Platinum ($48,800/kg) which improves workability.
The article mentions using the metallic glass to fabricate nuclear reactor vessels. It would indeed be interesting to see how this amorphous alloy reacts to intense ionizing radiation, particularly with neutrons. Most supercooled amoprhous materials expand when irradiated, then shrink when heated above their gelation-point temperature. This is how ordinary insulative shrink-tubing works; it's been irradiated until it expands to two to five times its original size. Just heat it up a bit and it shrinks again. I wonder how much this amorphous alloy expands?
toughness is the ability to resist breakage, a material's resistance to the starting and spreading of faults such as cracks. It often but not always goes along with "elasticity," or the ability of a material to flex under stress and yet not suffer faults for it, and recover nearly completely once the stress is removed. "maintaining strength under stress" is a good definition of tough. And by glass, I'm sure she means an amorphously-organized solid; not a crystal. That's the general definition. BTW, a glass can be composed of nearly any element(s), so long as that is its organizational principle. Glasses can be transparent, and the ones we see most are so, as that is the quality we like in them. Inclusions are also common; glasses are only rarely pure anything. Lead and quartz are common additives.
There's a lot of testing to do. Especially with a glass, we need to know HOW tough it is, and what its failure modes and manufacturing risks are, before we are free to build critical systems with it. There may well be ways that it can fail all at once and spectacularly (shatter), or it might be very (too) dependent on precise alloying techniques to be anything but a niche player.
Sorry Boonsri, but you're unusually vague. what do you mean toughness? I know that person can be tough, but material? I heard about hardness, tensile strength, elasticity, but toughness?... Also, what do you mean by glass? The glass like amorphous structure only, or actual transparency? Is it that it is too secret to tell the minimal details? So maybe you won't write about things that you're not able to write about? Hmm?
What's with the photo above? Is this a new Rorschach test picture? To me it looks like somebody with a goiter, spewing glass out of their nose, mouth and chin. Let me know when I can get unbreakable crystal champagne flutes, preferably without the nose hairs.
In terms of damage resistance, the focus will shift to the joint with other lesser materials. Interesting developments ahead...
So many obvious questions. The details are top secret. Price will reflect demand (also obvious). Wait for peer review.
So, a few questions. What is the melting point of the material? The reason why I ask is that if the material is light enough and has a high enough melting point you might make an engine out of it with a block that won't crack. What is the cost to create an item from the material, and is it likely to get cheap enough for common uses once you get to scale it up? What about drill bits made from this material? Does it conduct or insulate? What is meant by stronger/tougher. Are we talking about having a thread able to lift a certain weight before snapping? When it does break, what kind of break occurs, does the end snap or shred?
We are used to thinking that glass is transparent, even though there are some that are quite opaque. Metallic glass is as opaque as the normal metal crystals. The interesting thing is that the metallic glass is made up of several elements that keep the metals from crystalizing. The article did not talk about other properties such as conductance and magnetism.
First use could be solar panels. Then bullet proof glass for car windows. Stop the scum from stealing radios