Nav: Home

Discovery could lead to jet engines that run hotter -- and cleaner

January 17, 2017

COLUMBUS, Ohio--Researchers here have made a discovery in materials science that sounds like something from the old Saturday morning cartoon Super Friends: They've found a way to deactivate "nano twins" to improve the high-temperature properties of superalloys that are used in jet engines.

The advance could speed the development of powerful and environmentally friendly turbine engines of all sorts, including those used for transportation and power generation.

The "nano twins" in question are microscopic defects that grow inside alloys and weaken them, allowing them to deform under heat and pressure. In the journal Nature Communications, engineers at The Ohio State University describe how tailoring an alloy's composition and then exposing it to high heat and pressure can not only prevent nano twins from forming, it can actually make the alloy stronger.

In tests, the technique, which they've dubbed "phase transformation strengthening," eliminated the formation of nano twins and decreased alloy deformation by half.

Strong, heat-resistant alloys enable turbine engines to run cleanly and efficiently, explained Michael Mills, professor of materials science and engineering and leader of the project at Ohio State. When an engine can run at very high temperatures, it consumes its fuel more thoroughly and produces lower emissions.

"We found that increasing the concentrations of certain elements in super-alloys inhibits the formation of high-temperature deformation twins, thereby significantly improving the alloys' high temperature capabilities," Mills said.

These days, the most advanced alloys are designed on computer--practically atom by atom--and Mills' team set out to address what he called a deficit in the "quantitative, comprehensive understanding" of how these exotic metal-based materials deform under high stress.

The researchers made the discovery when they were studying nano twin formation in two different commercial superalloys. They compressed samples of the alloys with thousands of pounds of pressure at around 1,400 degrees Fahrenheit--a temperature comparable to a running jet engine--and afterward examined the alloys' crystal structures with electron microscopes and modeled the quantum mechanical behavior of the atoms on a computer.

In both alloys, the temperature and pressure caused nano twin faults to develop within the superalloy crystals. And, in both alloys, the material composition in and around the faults changed, but in different ways.

Through a sequence of atomic-scale jumps, some elments--such as atoms of nickel and aluminum--diffused away from the faults, while others diffused into the faults. The researchers were able to detect these fine-scale movements using the advanced electron microscopes at the Ohio State's Center for Electron Microscopy and Analysis (CEMAS), which offers one of the largest concentrations of electron and ion beam analytical microscopy instruments in any North American institution.

"In the first alloy, which was not as strong at high temperature, atoms of cobalt and chromium filled the fault," said Timothy Smith, former student at Ohio State and lead author of the study. "That weakened the area around the fault and allowed it to thicken and become a nano twin."

But in the second alloy--the one that didn't form nano twins--the elements titanium, tantalum and niobium tended to diffuse into the faults instead. As a result, a new and very stable phase of material formed right at the faults. The new phase was so stable that it resisted the formation of nano twins.

The tendency for particular atoms to diffuse into the nano twin faults depends on the overall composition of the alloy, the researchers found. "We discovered that when the amount of titanium, tantalum, and niobium in the alloy was increased, while decreasing cobalt and chromium, we could actually strengthen the region around the faults and prevent the fault from widening into a nano twin," Smith said.

The researchers' innovative combination of atomic-level imaging and high-end computing is a unique feature of research done at CEMAS, said David McComb, study co-author and director of CEMAS.

"Research such as this perfectly illustrates the power of CEMAS to help drive discovery in new materials and processes," he added.

The team is continuing to study phase transformation strengthening, to see if tailoring the alloy compositions in different ways might enhance the effect.

Smith earned his doctoral degree performing this work, and is now a research materials engineer at NASA Glenn Research Center. The paper's co-authors included Robert Williams, assistant director of CEMAS; Wolfgang Windl, professor of materials science and engineering; Hamish Fraser, Ohio Eminent Scholar and professor of materials science and engineering; and doctoral students Bryan Esser and Nikolas Antolin, all of Ohio State; Anna Carlsson of FEI/Thermo Fisher Scientific; and Andrew Wessman of GE.
-end-
This research was funded by the GE University Strategic Alliance, National Science Foundation, Center for Emergent Materials, Air Force Office of Scientific Research, and Center for the Accelerated Maturation of Materials. FEI provided access to, and assistance with, its Themis transmission electron microscope, and the Ohio Supercomputer Center provided computing time for the project.

Contact: Michael Mills, 614-643-3463; Mills.108@osu.edu

Written by Pam Frost Gorder, 614-292-9475; Gorder.1@osu.edu

Ohio State University

Related Atoms Articles:

Stenciling with atoms in 2-dimensional materials possible
The possibilities for the new field of two-dimensional, one-atomic-layer-thick materials, including but not limited to graphene, appear almost limitless.
Microprocessors based on a layer of just 3 atoms
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics.
Super sensitive devices work on recycling atoms
Next-generation sensors to be used in fields as diverse as mineral exploration and climate change will be turbo boosted thanks to University of Queensland and University of Sussex research.
Breakthrough with a chain of gold atoms
The precise control of electron transport in microelectronics makes complex logic circuits possible that are in daily use in smartphones and laptops.
Sorting machine for atoms
Physicists at the University of Bonn have cleared a further hurdle on the path to creating quantum computers: in a recent study, they present a method with which they can very quickly and precisely sort large numbers of atoms.
Boron atoms stretch out, gain new powers
Ribbons and single-atom chains of boron would have unique physical and electronic properties, according to theoretical physicists at Rice University.
ANU demonstrates 'ghost imaging' with atoms
A team of physicists at the Australian National University have used a technique known as 'ghost imaging' to create an image of an object from atoms that never interact with it.
'Weighing' atoms with electrons
The chemical properties of atoms depend on the number of protons in their nuclei, placing them into the periodic table.
New approach to determining how atoms are arranged in materials
Researchers have developed a novel approach to characterizing how atoms are arranged in materials, using Bayesian statistical methods to glean new insights into the structure of materials.
Magnetic atoms arranged in neat rows
Physicists at Friedrich-Alexander Universität Erlangen-Nürnberg and the Vienna University of Technology have successfully created one-dimensional magnetic atom chains for the first time.

Related Atoms Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Climate Crisis
There's no greater threat to humanity than climate change. What can we do to stop the worst consequences? This hour, TED speakers explore how we can save our planet and whether we can do it in time. Guests include climate activist Greta Thunberg, chemical engineer Jennifer Wilcox, research scientist Sean Davis, food innovator Bruce Friedrich, and psychologist Per Espen Stoknes.
Now Playing: Science for the People

#527 Honey I CRISPR'd the Kids
This week we're coming to you from Awesome Con in Washington, D.C. There, host Bethany Brookshire led a panel of three amazing guests to talk about the promise and perils of CRISPR, and what happens now that CRISPR babies have (maybe?) been born. Featuring science writer Tina Saey, molecular biologist Anne Simon, and bioethicist Alan Regenberg. A Nobel Prize winner argues banning CRISPR babies won’t work Geneticists push for a 5-year global ban on gene-edited babies A CRISPR spin-off causes unintended typos in DNA News of the first gene-edited babies ignited a firestorm The researcher who created CRISPR twins defends...