Leonard Kelley holds a bachelor's in physics with a minor in mathematics. He loves the academic world and strives to constantly explore it.
Metals have a strong allure to us. Whether it be for its intrinsic properties like weight or reflectivity or for its applications in material sciences, metals do provide plenty for us to like. It is this fascination that has led to some interesting discoveries and surprises at the edges of known physics. Let’s take a look at a sampling of these and see what we can find that may just blow your mind even further on the topic of metals.
The best surprises are often in response to something completely contrary to your expectations. This is what happened to Michael Tringides (U.S. Department of Energy’s Ames Laboratory) and team when examining a low temperature silicon surface and how lead atoms responded when deposited onto said surface. The expectation was the atoms would have random movement, slowly collapsing into a structure as collisions and loss of thermal energy increased. Instead, the lead atoms rapidly collapsed into a nanostructure despite the cold temperatures and supposedly random motion atoms exhibit on a surface. As to the full cause of this behavior, it could stem from electromagnetic considerations or electron distributions (Lucchesi).
Metal Organic Frameworks (MOFs)
When we can get a scaled down version of something we see frequently, it helps to articulate and demonstrate its usefulness. Take MOFs, for instance. These are 3D structures with a large surface area and are also capable storing large volumes of “gases such as carbon dioxide, hydrogen, and methane.” It involves a metal oxide in the center of organic molecules that together form a crystal structure that allows materials to remain trapped inside each hexagon without the usual pressure or temperature constraints of traditional gas storage. Most of the time, the structures are found via happenstance rather than by a methodology, meaning that the best storage method for a situation may remain unused. That started to change with a study by Omar Yaghi (Berkeley Lab) and team. Yaghi, one of the original discoverers of MOFs in the 1990s, found that using in-situ small angle X-ray scattering along with a gas absorption apparatus revealed that gases interacting around the MOF create pockets stored in the MOF roughly 40 nanometers in size. The materials of the gas, the MOF, and the lattice structure all impact this size (Yarris).
Metal like a Fluid
In a remarkable first, scientists from Harvard and Raytheon BBN Technology have found a metal whose electrons move about in a fluid-like motion. Normally, electrons don’t move like this because of the 3D structure of metals. This is not the case with the observed material being graphene, the wonder of the modern material world whose properties continue to amaze us. It has a 2D (or 1-atom thick) framework which allows the electrons to move in a unique fashion for metals. The team uncovered this ability by starting with a very pure sample of the material made from using “an electrically insulating perfect transparent crystal” whose molecular structure was similar to graphene’s and looked at the thermal conductivity of it. They found electrons in graphene move fast –almost 0.3% that of the speed of light- and that they collide about 10 trillion times a second! In fact, the electrons under an EM field seemed to follow fluid mechanics very well, opening the door for the study of relativistic hydrodynamics (Burrows)!
If we could attach metal to any surface we wanted to, could you imagine the possibilities? Well, imagine no more as it’s now a reality thanks to research from Kiel University. Using an electro-chemical etching process, the surface of our metal is disrupted on a micrometer scale, much like what is done with semiconductors. Any surface irregularities which inhibit bonding are removed and tiny hooks are created via the etching process to layers as deep as 10-20 micrometers. This renders the metal intact and doesn’t destroy their overall structure, just altering the surface in a desired fashion to allow adhesion to occur between materials once a polymer is applied. Interestingly, this bond is very strong. In strength tests either the polymer or main body of metal failed but never the site of the bonding. The connections still held up even when treated with surface contaminants and heat, meaning that some weather applications as well as surface treatment process are a possible application (Pawlowski).
Yes, such a thing exists, but not to chew on. These materials are quite malleable but how they do it was quite mysterious for the inherent structure of metal doesn’t lend itself to such behavior. But research from MPIE offers some new clues to decipher. The team examined a titanium-niobium-tantalum-zirconium alloy using X-rays, transmission electron microscopy, and atom probe tomography while being bent. The crystal-like structure seemed to bend out like honey does rather than shatter, based on the diffractions seen during the trial. It revealed a new phase for metals unseen before. Normally, a metal is either in an alpha phase, at room temperatures, or a beta phase, at high temperatures. Both are variations on rectangular structures. The titanium alloy introduced the omega phase, which instead involves hexagons, and it occurs between the alpha and beta phases. It can occur if a metal in a beta phase cools rapidly, forcing some of the molecules to go to an alpha phase because of the easier energy considerations there. But not everything is moving to that state equally, causing stresses to form in the metal structure and if too much is present then the omega phase occurs. Then once the stresses are gone, the full transformation to an alpha phase is achieved. This could be the mystery component that gum metal researchers have been looking for years and if so could maybe be extended to different types of metals (Salem).
Another development with gummy metals has been the improved ability to cut into them. As their name implies, gummy metals don’t cut very easily as a result of their make-up. They don’t give clean cut pieces but instead seem to crumple upon itself as energy is displaced inefficiently. Different elements can make the surface easy to cut, but only because it will actually alter the composition to the point of no return. Surprisingly, the most effective method is…markers and glue sticks? Turns out, these just add a stickiness to the surface that allows for a smoother cut by adhering the blade to the surface and mitigates the wobbly nature of a gummy metal cut. It has nothing to do with a chemical change but instead a physical alteration (Wiles).
Obviously, this is but a small sampling of the fascinating offerings metals have brought to us recently. Come back often to see new updates as metallurgy advancements continue.
Burrows, Leah. “A metal that behaves like water.” Innovaitons-report.com. innovations-report, 12 Feb. 2016. Web. 19 Aug. 2019.
Lucchesi, Breehan Gerleman. “’Explosive’ Atom Movement is New Window into Growing Metal Nanostructures.” Innovations-report.com. innovations-report, 04 Aug. 2015. Web. 16 Aug. 2019.
Pawlowski, Boris. “Breakthrough in materials science: Kiel research team can bond metals with nearly all surfaces.” Innovaitons-report.com. innovations-report, 08 Sept. 2016. Web. 19 Aug. 2019.
Salem, Yasmin Ahmed. “Gum metals pave the way for new applications.” Innovaitons-report.com. innovations-report, 01 Feb. 2017. Web. 19 Aug. 2019.
Wiles, Kayla. “Metal too ‘gummy’ to cut? Draw on it with a Sharpie or glue stick, science says.” Innovations-report.com. innovation-report, 19 Jul. 2018. Web. 20 Aug. 2019.
Yarris, Lynn. “A new way to look at MOFs.” Innovations-report.com. innovations-report, 11 Oct. 2015. Web. 19 Aug. 2019.
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
© 2020 Leonard Kelley