A renaissance is underway in materials science, and especially in metals design, fabrication, and characterization, says MIT Materials Processing Center Director Carl V. Thompson.
“No longer are simulations serving the purpose of explaining what’s already known. Things are now at the point where you can predict what a material will do and then see if that’s true in the laboratory and often find that it is,” Thompson said in remarks opening the Materials Day Symposium, hosted by the Materials Processing Center at MIT on Tuesday, Oct. 21. Thompson is the Stavros Salapatas Professor of Materials Science and Engineering at MIT.
New techniques such as data mining of scientific literature allow researchers to make best guesses about the crystal structures that a given set of elements will form and the properties of those crystals before they’re ever synthesized, driving a renaissance across materials science, but especially in metals research, he says.
Sixty-seven industry representatives joined 51 MIT participants for the daylong Materials Day Symposium, which was followed by a poster session. In all, 66 posters were presented.
Advanced high-strength steels
The Department of Energy-funded Integrated Computational Materials Engineering (ICME) of Generation Three Advanced High Strength Steels project is working to increase steel strength and reduce vehicle weight. “I believe that the best years in research of advanced high-strength steels are ahead of us,” says GM Technical Fellow Louis G. Hector Jr., a principal investigator on the project. “By no means do we understand everything that there is to know about these materials.”
The ICME project set out to answer the question, “Can we design new multiphase steels computationally with minimal experimental inputs such that a steel manufacturer can economically make large quantities, large meaning about 100,000 kilograms (about 110.23 U.S. short tons) of these materials with existing infrastructure to specified automotive component performance targets for mass reduction, strength, ductility, and so on?”
Collaborators including the Colorado School of Mines produced a duplex Transformation Induced Plasticity (TRIP) steel that meets one of the project targets, a new steel designed to absorb pressure up to 1,200 megapascals (MPa) without fracturing and to stretch up to 30 percent elongation without breaking, says Hector, who is based at GM R&D Center’s Chemical and Material Systems Lab in Warren, Mich.
Controlling nanostructured grains
Adding an alloying element that segregates to the grain boundaries of a base metal is the key to controlling nanoscale grain size in commercially-important metals such as nickel, silver, and aluminum, says Christopher A. Schuh, head of the Department of Materials Science and Engineering at MIT.
Research initiated at Schuh’s lab at MIT and continuing both on campus and through a spinoff, Xtalic, produced breakthroughs in nanostructured materials with grain sizes down to 10 or 20 nanometers and led to commercialization of the technology.
The initial nickel-tungsten coatings improved corrosion and wear resistance of copper connectors widely used in electronic applications and also reduced the need for the gold top coating over the nickel by two-thirds. “This is a case where a nickel’s worth of metallurgy saves you a lot of metal,” Schuh says. Now Xtalic is developing a gold substitute.
Additive manufacturing dramatically cut production time and costs for brackets used in the Juno spacecraft, which is headed to Jupiter, says Lockheed Martin Space Systems Co. Fellow Slade Gardner.
“By using additive manufacturing, we were allowed to take half the cost out and half the schedule out for these parts that did go on the Juno spacecraft,” Gardner says.
In general, additive manufacturing processes save 50 percent of cost and 80 percent of the time compared to traditional parts manufacturing, Lockheed Martin case studies show. “Both of those are key metrics when you’re facing the deadlines of a program,” Gardner says.
With robotic clusters, the additive manufacturing process may eventually extend to producing an entire spacecraft on a factory floor. Besides aerospace, new alloys and processing methods are needed across a range of applications from defense to energy, Gardner says.
New rare-earth metal process
Natick, Mass.-based Infinium Inc. developed a new separation process for rare-earth metals that promises a cleaner, cheaper source and less dependence on Chinese imports for the critical ingredient in hybrid/electric vehicles.
Infinium, originally founded in 2008 as Metal Oxygen Separation Technologies (MOxST), uses a technology known as solid-oxide membrane (SOM) electrolysis. It combines an SOM anode with a patented solid yttria-stabilized zirconia (YSZ) electrolyte and a molten-fluoride salt electrolyte. The electrolysis cell separates the metal oxide into oxygen gas and a metal-argon vapor. A condenser liquefies the metal, while the argon gas recirculates.
"To avoid some of the traditional problems with molten-fluoride electrolysis, we insert this zirconia solid electrolyte between the molten salt bath and the anode on the inside. So now we have two electrolytes essentially, a liquid electrolyte and a solid electrolyte. This has a wide variety of advantages. It enables new classes of inert anodes, such as liquid metals," says Adam C. Powell IV, PhD '97, chief technology officer and co-founder of Infinium. Powell served from 1999 to 2006 as the Thomas B. King Assistant Professor of Materials Engineering at MIT.
Infinium Metals announced on Oct. 21 that it is moving into commercial production of rare-earth metals, with an initial offering of dysprosium-iron this year, followed by a planned rollout next year of neodymium, and later didymium.
In addition to rare earths, Infinium's technology enables direct magnesium oxide (MgO) electrolysis and promises cleaner magnesium production, Powell says.
Although corrosion is an age-old problem, MIT Associate Professor of Nuclear Science and Engineering Bilge Yildiz believes it is ripe for new scientific discoveries.
She is working to engineer better alloys to prevent problems like cracking caused by hydrogen getting into metals such as zirconium alloys used in nuclear applications or iron-based alloys used in other applications.
Hydrogen absorption makes metal more susceptible to cracking. It has been known since the 1960s to avoid nickel, for example, in zirconium alloys. Yildiz and colleagues modeled how adding various transition metals affected hydrogen solubility of zirconium oxide. "Solubility of hydrogen into the zirconium oxide will determine how easy it will be to push hydrogen through this layer into the metal; the lower the solubility, the harder the transport through it," Yildiz says.
Yildiz's studies yielded insight into hydrogen solubility as a function of the electronic structure of the surface-oxide film. "There is a clear dependence of the electronic structure that alters the formation energies that then reflects to solubility of hydrogen," Yildiz explains. She hopes to extend the methods developed in the zirconia studies to other important industrial metals such as austentic steels.
Customizing metals for oil and gas
The boom in unconventional fuel resources in North America brought Schlumberger an opportunity to develop a new high-strength metal that could dissolve quickly in the presence of water. Schlumberger responded by developing dissolvable metal balls made of a water degradable aluminum alloy for use in hydrofracturing operations for recovering gas from shale. Such balls are used in multistage stimulation systems.
"Our metal is strong, particularly in compression, and meets oilfield needs for frac balls as first application. It is a precipitation-hardened aluminum alloy friendly to low-cost manufacturing," Manuel Marya, materials engineering manager at the Schlumberger Enabling Technologies Group, explains. "The metal exhibits a very peculiar structure of nanorods and nanoplatelets, as investigated by university partners, and is proven to be quite easy to manufacture in high volume and at appealing costs." Marya highlighted the multiple materials challenges facing a company like Schlumberger.
On the exploration and production side of the oil and gas industries, capital spending is rising at 6 percent per year while operating expenses rose 9 percent in the last year. Production is increasing at just over 1 percent per year. "So, you have a situation where the cost of development is going up faster than the supply is going up. And this really sets the stage for some drivers for the industry," says J. David Rowatt, research director at Schlumberger-Doll Research. "The prize — the oil and the gas — is getting harder and harder to get. The cost is going up; and new sources are more technically challenging to get to."
Making oxygen on the moon
Techniques of molten oxide electrolysis (MOE) can stretch from refining structural metals on earth to producing oxygen to support life on the moon, MIT Professor Donald R. Sadoway says. That's because the same process that extracts iron and other metals from their metal oxides releases oxygen as a byproduct.
There is sufficient metallic oxide content in the lunar surface to use molten oxide electrolysis to make oxygen from iron and sodium oxides, as well as from more plentiful aluminosilicates, oxygen-rich solid compounds of aluminum and silicon. "It doesn't matter where you go on the moon, you'll be able to use MOE and make oxygen," says Sadoway, who is the John F. Elliott Professor of Materials Chemistry in the Department of Materials Science and Engineering at MIT.
Sadoway and MIT colleagues have been studying molten-oxide electrolysis techniques for separating a variety of metals, from iron to titanium for carbon-free production in a single step.
Poster session winners
This year’s Materials Day poster session winners, all MIT graduate students, were Joseph Azzarelli of the Department of Chemistry and Zachary C. Cordero and Michael Gibson, both of the Department of Materials Science and Engineering. Azzarelli’s poster, “Wireless Detection of Gases and Vapors with a Smartphone via Near Field Communication,” was advised by Professor Timothy M. Swager. Cordero’s poster, “Powder Processing of Ultrafine Grain, Tungsten-bearing Alloys,” was advised by Chris Schuh. And Gibson’s poster, also advised by Schuh, was “Trends in Segregation Energies and Their connection to Embrittlement.”