Let It Snow Crystalline Dendrites
Image of snowflake-like crystalline dendrite wins first annual Jacobs School of Engineering Art Contest
|Crystalline dendrite imaged by transmission-mode Scanning Electron Microscopy. Image credit: Kevin Kaufmann|
Story by Lisa Adamiak
San Diego, Calif., Nov. 16, 2017 -- It’s extremely rare to spot a snowflake in sunny San Diego. But nanoengineering Ph.D. student Kevin Kaufmann routinely sees snowflakes through the lens of a microscope at UC San Diego—well, crystalline dendrites that resemble picturesque snowflakes.
|Photos by Liezel Labios/UC San Diego Jacobs School of Engineering|
The image of a crystalline dendrite shown above is the winning entry of the first annual Jacobs School of Engineering Art Contest. The contest provided engineers at UC San Diego an opportunity to share their research through original artwork. Submissions included photography, microscopy images, computer graphics illustrations, journal cover art, and other media.
Kaufmann received a $100 Visa gift card for his winning entry, which is featured on the Jacobs School website and social media. Entries that received an honorable mention will also be shared on the Jacobs School blog, Facebook, Instagram and Twitter accounts in the coming weeks.
Kaufmann works in the lab of nanoengineering professor Kenneth Vecchio, where he makes and studies metal alloys made of crystalline dendrites. Kaufmann captured the image of one of these crystalline dendrites using a method called transmission-mode Scanning Electron Microscopy (tSEM). This method produces images of a sample by bombarding the surface of the sample with a beam of electrons. The interactions between the electron beam and the sample then produce signals that relay information about the composition and surface features of the sample.
In his work, Kaufmann investigates the mechanical properties of a class of materials called bulk metallic glass composites, which are metal alloys that have a random arrangement of atoms (like glass). These composites are made by first melting them into a liquid to randomize the atomic arrangement, then cooling them at a rate fast enough to prevent the atoms from forming an ordered lattice. The resulting materials are essentially hybrids that contain both crystalline and non-crystalline phases.
The tSEM image that Kaufmann captured illustrates the crystalline dendrite phase encased in a non-crystalline matrix made from titanium-copper-based components. One of the goals of Kaufmann’s research is to tune the crystalline phase of bulk metallic glass composites. He has made a series of titanium-copper-based composites with varying levels of crystallinity. He found that increasing the crystallinity in turn increases the material’s ductility, which is the ability to stretch without breaking.
“These alloys have a high glass forming ability and therefore solidify into bulk metallic glass composites with predictable phase fractions at moderate cooling rates,” Kaufmann explains.
Kaufmann envisions that this work will be useful for designing new composites for a variety of applications ranging from consumer electronics to sporting equipment and even gears for spacecraft.
Long-term plans include applying the findings of this research to the manufacture of durable consumer products. “As technology and the world's requirements for advanced materials continue,” says Kaufmann, “my goal is to enhance the strength, toughness, and otherwise improve engineering properties of new materials.”