The team, led by nanoengineering professor Michael Demkowicz, published their findings October 10, 2022 in the journal Nature Materials.
"If we understand the origins of mechanical fracture, we can design ways to stop failure at its infancy," said Demkowicz.
Demkowicz and his collaborators investigated how fractures begin at nano-scale crystal defects on solid surfaces. Once initiated, these cracks can grow with little to no force being applied to the material, rendering devices useless or even dangerous.
The team observed that the fracture process at the crystal defect is highly dynamic—involving changes in the underlying atomic bonding. They made observations with a cutting-edge scanning tunneling microscope that combines low-temperature cryogenic capabilities, mechanical deformation, and a unique capability to probe changes in the material’s electronic structure at the atomic scale.
"Our scanning probe combines an array of experimental methods to monitor mechanical behavior and nanoscale electronic phenomena under extreme conditions, which had previously been impossible," said Demkowicz.
Through direct visualization of the fracture behavior and electronic properties, the team linked fracture processes to the quantum nature of the underlying atomic structure.
By chemically altering the bonds at the nanoscale crack tip the team could suppress the crack from propagating, thus improving the material's toughness.
The researchers suggest that the results could provide new directions for the design and development of mechanically robust materials and devices used in a wide range of applications, from aircraft to biomedical implants and electronic devices.
"This discovery highlights the fact that the origins of fracture are highly dynamic, and it allows us to envisage routes for engineering materials and device geometries that are resistant to failure," said Demkowicz.
Reference:
Kaitlin O’Brien, Benjamin J. McEnaney, Michael J. Cawkwell, James Ciston, and Michael J. Demkowicz, “Suppression of nanoscale fracture by chemical control of crack-tip electronic structure,” Nature Materials (October 10, 2022). DOI: 10.1038/s41563-022-01334-0.
