“We had the answer all this time, but we just weren’t looking for it.”
Great Scott! A group of BYU researchers have traveled back in time to solve a seemingly irreconcilable scientific mystery that has confused engineers and chemists for nearly two decades.
And while they didn’t actually hit 88 miles an hour in a DeLorean like Michael J. Fox, the team did end up in the same time frame as Marty McFly, where they found the answer to a metals processing conundrum that has popped up in modern academic research. Turns out there is an old mathematical model from 1950s-era research that explains the phenomenon and reconciles the counterintuitive results.
“I guess this is the classic, ‘old things become new’ scenario,” said lead researcher Eric Homer, a BYU professor of mechanical engineering. “We had the answer all this time, but we just weren’t looking for it.”
The problem in question has appeared in a series of experiments and simulations since the early 2000s and it has to do with the speed of material processes in relation to temperature. Material processing often occurs in a series of thermal and mechanical treatments to evolve the material structure to achieve optimal properties such as strength and ductility. Think of a modern version of a blacksmith that heats and beats metals into all sorts of finished parts or products, such as jet turbines, automobile frames and panels for cars like Teslas — the DeLorean’s contemporary counterpart with the falcon-wing doors. The heat and deformation play an important role besides just shaping the part, it affects the ability of the part to withstand the strain it will be subjected to.
It is widely known among material engineers that most material processes occur faster at higher temperatures. (For the non-engineers/scientists out there, consider how hot chocolate mix dissolves faster in hot water than cold water.)
However, 20 years ago simulations and experiments of specific scenarios started getting the opposite results when it came to metal fabrication, where processes were happening faster at colder temperatures — specifically cryogenic temperatures.
Engineers, physicists, scientists, and researchers were all stumped. They couldn’t figure out how to reconcile something that seemed to be operating outside of the conventional theories that have explained more than one hundred years of research and industrial applications.
Emmett Brown Homer, BYU undergrad Darcey Britton, fellow BYU professors Oliver Johnson, James Patterson, Eric Sevy, and colleague Gregory Thompson, a BYU alumnus and professor at the University of Alabama. In a new academic article published in Nature partner journal, Computational Materials, they detail how the solution was really under everyone’s noses.
“We went back in the literature and found that the equation most people use is actually a simplification on a more complex equation from the 1950s,” Homer said. “If you plug all your factors into the old, complex equation, it predicts and explains exactly why material processing can speed up at both hotter and colder temperatures.”
The key, Homer said, is that the energies for the processes are very small so even a little bit of energy (i.e. liquid nitrogen temperature) is enough to start the process. “But weirdly, the low energy processes are frustrated by additional energy, not helped by it, which is why it's faster at cryogenic temperature than room temperature.”
The takeaway from this very nerdy, but exciting discovery is that it may open the door to the fabrication of both stronger and lighter metals under very different conditions used today — exactly what many industries (like Tesla and the car industry) want and need.
In the words of Marty McFly: “This is heavy.” Well, actually, the opposite of heavy, but still.