Strong as steel. Atom probe tomography suggests that packing zinc and magnesium atoms together in groups of various sizes (small spots) can greatly improve the strength of aluminum alloy.
Credit: University of Sydney
Posted on 10/01/2010 3:11:46 PM PDT by neverdem
Snuffing out a cigarette butt with a 10-ton boot would be excessive, but using the equivalent on certain metals can yield amazing results. By smashing an aluminum alloy between two anvils, researchers have created a metal that's as strong as steel but much lighter. If the process can be commercialized, it could yield better components for aircraft and automobiles, as well as metal armor light enough for soldiers to wear in battle.
Aluminum's main advantage is its lightness. But the most abundant metal in Earth's crust is also a weakling: It breaks apart under loads that heavier metals such as steel shoulder easily. For decades, scientists have been looking for a way to manufacture the aluminum equivalent of titanium, a lightweight metal that's stronger than steel, but without titanium's high cost.
In the new study, an international team of materials scientists turned to an emerging metal-processing technique called high-pressure torsion (HPT). Basically, HPT involves clamping a thin disk of metal to a cylindrical anvil and pressing it against another anvil with a force of about 60,000 kilograms per square centimeter, all while turning one anvil slowly. The researchers also kept the processed samples at room temperature for over a month, in a common metallurgical process called natural aging. The deformation under the enormous pressure plus the aging alters the basic structure of metals at the nanoscale—or distances measured in billionths of a meter.
And indeed, when the team subjected an alloy of aluminum called aluminum 7075 (which contains small percentages of magnesium and zinc) to the process, the metal attained a strength of 1 gigapascal, the researchers report in the current issue of Nature Communications. That's equal to some of the strongest steels and more than three times higher than conventional aluminum. A meter-square plate of the processed alloy could withstand the weight of a fully loaded aircraft carrier.
To find out why the alloy had gotten so much stronger, the team examined samples using a technique called atom probe tomography. Resembling a combination of an electron microscope and a CT scanner, the method showed that HPT had deformed the lattice of atoms in the alloy into an unprecedented arrangement. Instead of the normal structure found in the conventional metal, HPT had created what the researchers call a hierarchical nanostructure: the size of the aluminum grains was reduced, and the zinc and magnesium atoms clustered together in groups of various sizes, depending on whether they were located inside the aluminum grains or on the edges (see photo).
Exactly how this arrangement creates stronger aluminum is unclear, says co-author Simon Ringer, director of the Electron Microscope Unit at the University of Sydney in Australia. He says the atoms at the edges of the grains seem to be bonded tightly to atoms at adjoining grain edges. Whatever the physics, he says, the hierarchical structures are "very potent for strengthening."
Ringer adds that even though the experiments produced only laboratory quantities of the superstrength alloy, the process could quickly be adapted to produce small components that require high strength but low weight, such as biomedical implants. Co-author and materials scientist Yuntian Zhu of North Carolina State University in Raleigh says there is strong incentive to scale up the process because the alloy could be useful for "many lightweight, energy-efficient applications such as aerospace, transportation, and body armor."
The experiments "have achieved remarkable strength" in a conventional commercial aluminum alloy, says materials scientist Terence Langdon of the University of Southern California in Los Angeles. The research team has also demonstrated "the exceptional capabilities provided through processing by high-pressure torsion," a technique that Langdon and others have been working with for several years.
Materials scientist Yuri Estrin of Monash University in Melbourne, Australia, calls the results exciting and agrees that the hierarchical nanostructures "appear to be crucial to the spectacular enhancement of [the alloy's] strength."
Good stuff!
I’ve been investing in gold/silver/guns and bullets.
Also stocking up on cash.
Be Ever Vigilant!
Maybe that could work for an Aluminum framed firearm.
At the atomic scale, the great thing about iron is the high number of valence connection points, which allow for huge potential for bonding with other elements. it is also why it rusts, so if other elements could be bonded to iron atoms to shut the oxygen docking points, iron would also be ‘ageless’, so to speak. If our current understanding of Physics doesn’t mature to cancel temporal variables, we’re gonna need something that doesn’t decay over eons as it whizzes through the universe on the way to other star systems.
For no one - no one in this world can you trust. Not men, not women, not beasts.
"This you can trust."
“[Oil] won’t go down.”
Not right away. It takes a long time to develop new cars.
I’m no authority on oil, but as I understand it, the byproducts are plentiful as it is, and we primarily refine oil for gas, right?
I was wondering that myself. Is aluminum is flexible [obviously]. I guess that must have intrigued someone to test that flexibility out. Amazing how simple ideas cause such radical game-changers!
iron decays due to oxygen. there’s no oxygen in space. The problem with iron is it’s too heavy.
Auto exhaust pipes use a coating of aluminum on steel to inhibit rust. chain link fences and sheet metal use a coating of zinc to inhibit rust. Firearms use a coating of black oxide(rust bluing) to inhibit rust. Auto bumpers traditionally used a coating of nickel(chrome) to inhibit rust. There are two kinds of iron oxide. black and red. black is slightly like aluminum oxide in that it is partially impervious to air and water and prevents further oxidation...somewhat. It doesn’t work as good as aluminum oxide.
If I was to try to develop a coating on iron to prevent oxidation, I think I would look for something that bonds to black iron oxide and then mix it with iron so that it would be a self healing skin.
I wonder if similar techniques could be used to increase the strength of other metals.
LOL
Yes but I suspect that a little heat will alter the molecules and reduce the strength.
It's reading these blasted Klingon control labels that's the challenge.
Hooray for this iCorder app:
New cars that do what?
You've gotta love market capitalism and the profit motive!
I’m waiting for plastisteel before I hand build my space craft.
The hyper-drive is ready, although the oil industry is suppressing it along with my 1 million MPG fuel additive.
Stronger bodies that weigh less.
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