Making lighter vehicles with magnesium alloys

Making lighter vehicles with magnesium alloys
Shave just 100 kilograms off of a car’s weight and you’ll boost its energy efficiency by about 3.5%. Credit: iStock

EPFL researchers have developed models of magnesium alloys to understand how to make the metal more pliable. Magnesium is the lightest metal on earth but cannot easily be shaped into usable forms. The researchers hope that with the models will lead to the discovery of new, more malleable alloys, so that carmakers can make lighter vehicles that consume less energy.

Shave just 100 kilograms off of a car's weight and you'll boost its energy efficiency by about 3.5 percent. Making lighter machines and equipment is a goal of manufacturers in industries ranging from automotive to aerospace. And the key could just be – a metal that is not only four times lighter than steel, but is also easy to find. The catch is that pure magnesium is hard to stretch and form and so cannot be used as-is. So, researchers at EPFL's Laboratory for Multiscale Mechanics Modelling developed a model to predict how the metal behaves when mixed with different elements in order to determine which type of alloy provides the deformation capacity needed for industrial applications. Their research was published today in Science.

Lighter, more malleable alloys

"Magnesium becomes much more malleable if you add a few atoms of , calcium, or manganese," says William Curtin, a professor at EPFL's School of Engineering. "We wanted to understand what's going on in these at an atomic level, so that we can identify which elements to add and in what amounts to make the metal pliable." Magnesium may be appreciated for its ultra-low weight, but it also has very low ductility. "That means it can break easily if it's deformed, and so it can't yet replace steel or aluminum," says Curtin. The solution is to find low-cost, readily-available minerals that can be used to create . Rare-earth metals like yttrium and cerium are highly effective but otherwise do not meet these criteria.

Making lighter vehicles with magnesium alloys
The two figures show the initial and final atomic configurations of the "cross-slip" process in the presence of two Yttrium atoms. Blue atoms are Mg atoms that are nearly in the perfect Mg crystal environment, yellow atoms are Mg atoms that are far from the perfect Mg crystal environment, and so indicate the structure and atoms involved in the "dislocation" defect. Red atoms are two Y solutes. Credit: Ecole Polytechnique Federale de Lausanne

These researchers previously identified the physical properties that make pure magnesium hard to shape. It was well known that adding certain elements can make it more malleable. But researchers don't have a good grasp of the physical mechanisms taking place – meaning they have a hard time predicting what the best alloys would be. "Engineers often design and test new alloys of steel and aluminum, the most commonly used metals, to develop lighter, more solid or more malleable compounds," says Curtin. But the factors affecting an alloy's ductility remain a mystery and many materials are still developed experimentally.

Studying metals on an atomic scale

The EPFL researchers studied the interactions between magnesium atoms and the atoms of the elements added to make the alloys. They found that certain atoms trigger a process that "cancels out" the mechanism that makes magnesium hard to shape. Magnesium's low ductility is due to its low number of moveable dislocations, which are the linear defects that make metals flow plastically and that make it less likely to break when it's deformed. The researchers found that adding certain elements substantially increases the number of moveable dislocations and therefore enhances the 's deformation capacity. They then spent several months using EPFL's High Performance Computing system to calculate via quantum mechanics which combinations of atoms result in the highest ductility. "We were really lucky to have access to this equipment, which let us start working right away," says Curtin.

For now the alloys are still in the modelling stage. The next step will be fabrication in the lab to see if they have the right properties for industrial use and can be manufactured on a large scale.


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More information: Zhaoxuan Wu et al. Mechanistic origin and prediction of enhanced ductility in magnesium alloys, Science (2018). DOI: 10.1126/science.aap8716
Journal information: Science

Citation: Making lighter vehicles with magnesium alloys (2018, January 26) retrieved 19 April 2019 from https://phys.org/news/2018-01-lighter-vehicles-magnesium-alloys.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
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Jan 26, 2018
" The catch is that pure magnesium is hard to stretch and form and so cannot be used as-is. "

Not to mention the fact that it burns in a spectacular fashion.

Jan 26, 2018
Yes, a magnesium fire is something to watch. In the foundry industry we would add a Nickle-Magnesium alloy to a charge of molten iron to make Ductile Iron. It is a violently-exothermic process.

Jan 26, 2018
The Wiki article about Magnesium is very interesting. Such a variety of uses and very abundant.

One big advantage, I thought, is that it has a very low rate of biological toxicity compared to other metals.

That alone makes expanding research into new uses for Mg should be considered a priority.

Jan 26, 2018
Please fact check before saying things like, "Magnesium is the lightest metal on earth", since Ca, Rb, Na, K, & Li are all less dense than Mg. In fact lithium is less than ONE THIRD the density of magnesium! (0.535 vs 1.738 sp. gr.) check:→ periodictable.com/Properties/A/Density.ssp.log.html

Jan 27, 2018
B-29s returning from Japan would many times have to shut down over heating engines. Unfortunately the bearings would then overheat when the props were feathered. The magnesium would then light off and the crew were usually goners. This doesn't seem to be that much of a problem on Biackhawk helos.

Jan 27, 2018
so now there'll be even more unnecessary deaths from even less protective tin cans. Oh well, Sanger's ghost and Ehrlich will be doing handsprings of cheer.

Thanks, but I'll stay with my F-150 pickup and my 2004 Town Car. Great rides and built like tanks relative to the 'green' cars.

Jan 28, 2018
" Great rides and built like tanks relative to the 'green' cars."

Our Tesla Model S, P 85 is the safest car ever tested.

Sorry about your Pinto.

Jan 28, 2018
I'll gladly put my F-150 up against any Tesla ever made. It outweighs you by over 400 pounds, sits higher, has real bumpers. The Town Car passed all crash tests with 5's and rated safest. It weighs in the same weight class as the S model. [info: my Town Car Signature Series is a 2004 model which is the third series and one of the largest. The new ones, not so much]

Jan 28, 2018
I'll gladly put my F-150 up against any Tesla ever made. It outweighs you by over 400 pounds, sits higher, has real bumpers
lots of factors for impact survivability in a collision

?
are you talking frontal collision, off-set frontal, side or some other type? Is there an animal involved? what other conditions (terrain, location, EMS availability)?
?

human biomechanical loading also has a huge factor in survivability

I would definitely want to know the type of collision before deciding - it's all fun and games until somebody breaks their scapula in a frontal collision

.


Jan 28, 2018
"The Town Car passed all crash tests with 5's and rated safest."

Nope, the safest ever tested was the Tesla Model S. In the car crush test, it broke the crush machine. But enjoy your dinosaur.

Jan 29, 2018
The metallurgy is one thing the application to autos seems a little premature. Carbon and other fibers (like Kevlar) composites are moving down the learning curve fast and technologically advancing fast. The energy cost of ore extraction, electrolysis, casting, and forming seem a bit more expensive and less advantageous than carbon fiber. Obviously the mechanical properties are good if the 787 can be made of it. Go figure.

Jan 29, 2018
Carbon fiber will be revealed to have serious problems when a graphite aircraft burns on the runway and the smoke, consisting of sub-micron needles of carbon, conductive and opaque to RF, cloud radar and communications.

Jan 29, 2018
Carbon fiber will be revealed to have serious problems when a graphite aircraft burns on the runway and the smoke, consisting of sub-micron needles of carbon, conductive and opaque to RF, cloud radar and communications.


There is a difference between carbon, kevlar, boron, etc. loose fiber and fiber embedded in an epoxy composite. Boeing would not have invested $32B in the 787 had that been a potential liability. Everybody sues the deep pocket of an airline or aircraft manufacturer with the slightest cause.

If it is burning how does the carbon not turn into CO2? If carbon fiber can reduce auto weight by 12% and Mg by 3.5% with the commensurate reduction in gas or electrical use which would be the lesser of evils?

Better start shooting down all those drones because they are already composite carbon.

Jan 29, 2018
"If it is burning how does the carbon not turn into CO2?"

I am reporting the results of our tests for NASA on graphite fiber materials made for aircraft, in several configurations, supplied by NASA. Burning and impact scatters into a cloud of "smoke" electrically-conductive and respirable (down to sub-micron), fibers, shortened and ablated by the combustion and impact.

We did the tests in 1979. I think it has been weaponized.

Jan 29, 2018
"If it is burning how does the carbon not turn into CO2?"

I am reporting the results of our tests for NASA on graphite fiber materials made for aircraft, in several configurations, supplied by NASA. Burning and impact scatters into a cloud of "smoke" electrically-conductive and respirable (down to sub-micron), fibers, shortened and ablated by the combustion and impact.

We did the tests in 1979. I think it has been weaponized.


Speaking to carbon fiber only it is true they generally do not burn. Do we know there is a real risk from a fiber cloud. It doesn't seem as though it would shut down a transformer or car. Would a sub-micron particle falling on a circuit board create a short circuit?

Boeing knows something we don't as they are not going to consciously open themselves up to the equivalent liability of a Deepwater Horizon oil spill. Their pockets are to deep therefore every dirty shyster in the nation would be lining up for a piece of the action.

Jan 29, 2018
"It doesn't seem as though it would shut down a transformer "

It already did, which is why we got the study.

Jan 29, 2018
I am reporting the results of our tests for NASA...
We did the tests in 1979. I think it has been weaponized
George kamburoff the serial jobshopper never had a job long enough to become proficient in it. How do we know? He has confided here that he has had at least 15 of them, and then sat as a 'consultant' for perhaps a decade when HR dept screenings rendered him unemployable.

Getting a job to george meant far more than keeping one. It gave him the opportunity to claim expertise in yet one more field he knows nothing about.

"[Psychopaths] can be found in white collar professions where they are aided in their evil by the fact that most people expect certain classes of people to be trustworthy because of their social or professional credentials. Lawyers, doctors, teachers, politicians, psychiatrists and psychologists, generally do not have to earn our trust because they have it by virtue of their positions."
cont>

Jan 29, 2018
"They pick professions in which the requisite skills are easy to fake, the jargon is easy to learn, and the credentials are unlikely to be thoroughly checked. Psychopaths find it extremely easy to pose as financial consultants, ministers, psychological counselors and psychologists."

"What makes psychopaths different from all others is the remarkable ease with which they lie, the pervasiveness of their deception, and the callousness with which they carry it out."

Jan 29, 2018
@TheGhostofOtto1923

I think you have it.

Jan 29, 2018
Turge, perhaps they found ways around the phenomenon, . . I do not know. All know is what we tested, the many variations of weave and other fabrication, and the results.

I gave the reference to the NASA tests in earlier posts.

Turgent, I made the mistake of being straight with you, assuming you had some character.

Sorry about my error.

Jan 29, 2018


I gave the reference to the NASA tests in earlier posts..


Specifically cited, I missed it?


Jan 30, 2018
Turgent, I made the mistake of being straight with you, assuming you had some character
Character.

"A woman with a staggering record of fraud, deceit, lies, and broken promises concluded a letter to the parole board with, "I've let a lot of people down… One is only as good as her reputation and name. My word is as good as gold."

-Psychopaths are never out of character.

"Four days after the June 2016 Pulse nightclub shooting in Orlando, then-U.S. Rep. Corrine Brown descended the stairs of Air Force One in Orlando alongside President Barack Obama... sentenced last month for using about $800,000 meant for poor students to pay for Bahama vacations and a Beyoncé concert and to pad her own bank accounts"

"Bishop Kelvin Cobaris, lead pastor and founder of The Impact Church in Orlando and Brown's spiritual adviser, said she was accompanied by family to the prison about 50 miles northwest of downtown Orlando.

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