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A D V A N C E D M A T E R I A L S & P R O C E S S E S | O C T O B E R 2 0 1 9 1 5 PROCESS TECHNOLOGY BENDING METALS FOR MORE DURABLE MILITARY VEHICLES As part of a U.S. Army project, re- searchers at the University of Wiscon- sin-Madison have discovered a new understanding of the way metals can bend. The discovery upends previous notions about how metals deform and could help guide the creation of stron- ger, more durable materials for mili- tary vehicles. The researchers’ new mechanism for bending might allow engineers to strengthen a material without running the risk of fractures. “This creates new opportuni- ties for materials design,” says scien- tist Izabela Szlufarska. “It adds anoth- er parameter we can control to enable strength and ductility.” Normal metals bend because dis- locations can move, allowing a materi- al to deform without ripping apart ev- ery single bond inside its crystal lattice at once. Strengthening techniques typi- cally restrict the motion of dislocations. So, it was shocking when Szlu- farska and colleagues discovered that samarium cobalt, known as an interme- tallic, bent easily, even though its dislo- cations were locked in place. Bending samarium cobalt caused narrow bands to form inside the crys- tal lattice, where molecules assumed a freeform “amorphous” configuration instead of the regular, grid-like struc- ture in the rest of the metal. Those amorphous bands allowed the metal to bend. A combination of computational simulations and exper- imental studies was critical to explain- ing the result. “It is this type of fundamental re- search discovery that eventually results in the advanced materials that will pro- tect soldiers 25 to 30 years from now,” say researchers. arl.army.mil , wisc.edu . 2D MATERIAL STIFFER THAN STEEL Scientists at Rice University, Hous- ton, are modifying an insulating ma- terial called hexagonal-boron (h-BN) to make it more applicable for a wide range of applications. The 2D material, also known as “white graphene,” is four times stiffer than steel and an excellent conductor of heat—a benefit for com- posites that rely on it to enhance their properties. Those qualities also make h-BN hard to customize. Its tight hexagonal lattice of alternating boron and nitro- gen atoms is highly resistant to change. Rice’s Angel Martí has established a protocol to enhance h-BN with carbon chains. These turn the 2D material into one that retains its strength but is more amenable to bonding with polymers or other materials in composites. Lithium is an alkali metal that sheds free electrons when combined with liquefied ammonia. Mixed with h-BN flakes and a carbon source, 1-Bro- mododecane in this case, the reaction produces an alkyl radical, a chemi- cal species that reacts with h-BN and makes a bond. Martí and his group are exploring what other kinds of molecules can be grafted onto white graphene. The goal is to build a library of functional groups that can be used with composite mate- rials. rice.edu . UW-Madison researchers demonstrate a newmechanism for bending metal that could lead to more durable materials for military vehicles. Image courtesy of UW-Madison/SamMillion-Weaver. BRIEF Cleveland-Cliffs Inc., Cleveland, has launched a new environmental section on its corporate website. The environ- mental section provides a comprehensive look at Cliffs’ progress and outcomes in key areas of its environmental performance and its contribution to clean steelmaking. clevelandcliffs.com . Graphic depiction of the addition of carbon chains to hexagonal-boron nitride. Courtesy of Rice University/the Angel Martí Group.