Stronger than steel, novel metals are moldable as plastic

Mar 01, 2011
Jan Schroers and his team have developed novel metal alloys that can be blow molded into virtually any shape.

(PhysOrg.com) -- Imagine a material that's stronger than steel, but just as versatile as plastic, able to take on a seemingly endless variety of forms. For decades, materials scientists have been trying to come up with just such an ideal substance, one that could be molded into complex shapes with the same ease and low expense as plastic but without sacrificing the strength and durability of metal.

Now a team led by Jan Schroers, a materials scientist at Yale University, has shown that some recently developed bulk metallic glasses (BMGs)-metal alloys that have randomly arranged atoms as opposed to the orderly, found in ordinary metals-can be blow molded like plastics into complex shapes that can't be achieved using regular metal, yet without sacrificing the strength or durability that metal affords. Their findings are described online in the current issue of the journal Materials Today.

"These alloys look like ordinary metal but can be blow molded just as cheaply and as easily as plastic," Schroers said. So far the team has created a number of complex shapes-including seamless metallic bottles, watch cases, miniature resonators and biomedical implants-that can be molded in less than a minute and are twice as strong as typical steel.

The materials cost about the same as high-end steel, Schroers said, but can be processed as cheaply as plastic. The alloys are made up of different metals, including zirconium, nickel, titanium and copper.

The team blow molded the alloys at low temperatures and low pressures, where the bulk softens dramatically and flows as easily as plastic but without crystallizing like regular metal. It's the low temperatures and low pressures that allowed the team to shape the BMGs with unprecedented ease, versatility and precision, Schroers said. In order to carefully control and maintain the ideal temperature for blow molding, the team shaped the BMGs in a vacuum or in fluid.

"The trick is to avoid typically present in other forming techniques," Schroers said. "Blow molding completely eliminates friction, allowing us to create any number of complicated shapes, down to the nanoscale."

Schroers and his team are already using their new processing technique to fabricate miniature resonators for microelectromechanical systems (MEMS)-tiny mechanical devices powered by electricity-as well as gyroscopes and other resonator applications.

In addition, by blow molding the BMGs, the team was able to combine three separate steps in traditional metal processing (shaping, joining and finishing) into one, allowing them to carry out previously cumbersome, time- and energy-intensive processing in less than a minute.

"This could enable a whole new paradigm for shaping metals," Schroers said. "The superior properties of BMGs relative to plastics and typical metals, combined with the ease, economy and precision of blow molding, have the potential to impact society just as much as the development of synthetic and their associated processing methods have in the last century."

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Nik_2213
4 / 5 (4) Mar 01, 2011
This sounds like an ideal adjunct to rapid prototyping, which could turn out high precision moulds and, directly, low-stressed components...
Birger
3 / 5 (1) Mar 01, 2011
I would like to know if these metallic glasses deform rather than undergoing catastrophic brittle failure at maximum load before I purchase anything made of this material.
With metal (simplified description) you get some warning before the structure fails. Can you make springs from these materials? How much can they bend?
Eikka
3 / 5 (1) Mar 01, 2011
I would like to know if these metallic glasses deform rather than undergoing catastrophic brittle failure at maximum load before I purchase anything made of this material.


I believe they crystallize at the fracture, making the material there behave like ordinary metal.

Still, it can be quite catastropic unless the alloy that is re-formed lends itself to high tensile strenght in the "normal" mode.
GSwift7
4.9 / 5 (7) Mar 01, 2011
This sounds like an ideal adjunct to rapid prototyping


That may be true, but I think the real bonus here is the ability to cheaply mass-produce complicated metal parts with extremely tight tollerances. Think along the lines of auto body panels that have complicated trim features and attachment points molded right into the metal. You would also be able to use the molds thousands of times with this method, as opposed to the expensive dies they use to stamp out car body parts now which can only be used a few times before they go out of tollerance. I'll bet you could cut down the number of parts and fasteners in a car by a healthy percent with this method. Colored, corrosion resistant metals could even eliminate the need to paint. That would be cool.
GSwift7
4.5 / 5 (2) Mar 01, 2011
I would like to know if these metallic glasses deform rather than undergoing catastrophic brittle failure


Look up Amorphous Metal on wiki (bulk metal glass is one type). They say that the amorphous metals are more elastic than 'normal' alloys, and less brittle than other types of glass and ceramic. I get the impression that the exact composition can change the properties though, so the answer to your question will depend on exactly what materials you use. From what I have read though, the bulk metal glass they are talking about above seems to have a problem with large pieces due to problems with the rate of cooling. If it cools too slowly the metals will form crystals and become like a 'normal' alloy which produces fracture points inside the material. The pieces need to be small/thin so that they cool before the metal molecules get a chance to align and form crystals.
Shootist
3.5 / 5 (2) Mar 01, 2011
I want a material that only passes EM between 300nm and 800nm and stops 100% of fast neutrons, neutrinos and gamma.
Alphakronik
Mar 01, 2011
This comment has been removed by a moderator.
GSwift7
3.3 / 5 (6) Mar 01, 2011
I want a material that only passes EM between 300nm and 800nm and stops 100% of fast neutrons


[joke]
I want a material that only passes ballanced budgets and stops 100% of wasteful spending. Unfortunately, such a material would likely be declared a hazardous material by the EPA.
[/joke]
trekgeek1
4 / 5 (2) Mar 01, 2011
I would like to know if these metallic glasses deform rather than undergoing catastrophic brittle failure at maximum load before I purchase anything made of this material.


Really? Anything? I don't think a catastrophic failure of a pair of sunglasses would be a real concern. Even if these materials fail without warning, there are numerous non-critical applications that would benefit.
braindead
not rated yet Mar 01, 2011
Can the materials be easily recycled e.g. remoulded like thermo plastics as well?
Phaze
not rated yet Mar 01, 2011
i wonder if they are as temperature sensitive after molding
GSwift7
4.7 / 5 (3) Mar 02, 2011
i wonder if they are as temperature sensitive after molding


As with the previous question, that depends somewhat on the mixture of materials you use. That also depends on what you mean by 'temperature sensitive'. If you are talking about the temperatures involved in cooking on your kitchen stove, then I think these materials are generally okay in that range. The article above is a little misleading when he says that he used low temperatures to form the materials. You must understand that he's talking about low temperatures for the purpose of melting metals. The temperature range is still a lot higher than anything you would encounter in your daily life. As long as you don't get this kind of material hot enough to make it start to melt you shouldn't see any significant problems. Think of the glass in your car window. If you got it hot enough it would get soft too.

As for being brittle, compare this stuff to a composite tennis racket. Amorphous materials can be very though
Nathan_Phillips
4 / 5 (2) Mar 03, 2011
I want to see this being used in conjunction with 3D printing to produce high durability cell-phones, laptops and possibly Iron Man style armors. I think that larger pieces could be made as long as they are made quickly and possibly liquid nitrogen cooled.
Beard
4 / 5 (1) Mar 03, 2011
Plasteel!!!!
en.wikipedia.org/wiki/Plasteel_(Star_Wars)#Plasteel

I never thought I would see this in the real world so soon. Material science is so badass.
damnfuct
not rated yet Mar 05, 2011
The term "metallic glass" is misleading as some people think glass implies some level of transparency; in this case, the metallic nature means "metallic glasses" are just as transparent as a piece of regular metal. Using something like "amorphous alloy" is a much more descriptive term. These materials would be used in a similar manner to regular metals.
Moebius
1.5 / 5 (2) Mar 06, 2011
This sounds like a powder metal process which has been around for years and just an improvement on the alloys, a key detail the writer left out due to the usual complete unfamiliarity with the subject matter.
ECOnservative
not rated yet Mar 06, 2011
How ductile is the resulting solid and over what temperature range(s)? What about surface roughness? Can additional finishing be done or is it "mold and leave alone" like many ceramics and glasses? Interesting set of possibilities..
FastEddy
not rated yet Mar 07, 2011
en.wikipedia.org/wiki/Plasteel_(Star_Wars)#Plasteel

I never thought I would see this in the real world so soon. ...


How about http://en.wikiped...aluminum :>)
FastEddy
not rated yet Mar 07, 2011
And: http://en.wikiped...r_metals ... The world of material sciences is now expanding at a rate approaching Moore's Law ... Oh Boy!