Latest findings published in Nature
Researchers from the Max-Planck-Institut für Eisenforschung, Düsseldorf, and the University of Science and Technology Beijing discovered a new mechanism that enhances both the antagonistic strength and ductility in a high-entropy alloy.
The new mechanism is caused by the addition of oxygen in relatively high quantity, which alters the alloy’s microstructure and leads to an increase of strength by almost 50% and ductility of ca. 95%. The scientists published their latest findings in Nature.
Oxygen, which is usually neglected as an alloying element as it is known to cause embrittlement, is now added by 2.0 atomic percent in a model high entropy alloy (HEA) of TiZrHfNb.
The researchers studied the effect of oxygen on the microstructure of the HEA to understand the impact on strength and ductility.
They used different analysis techniques such as synchrotron high-energy X-ray diffraction, electron backscatter diffraction mapping and aberration corrected scanning transmission electron microscopy (STEM) high-angle annular dark field but could not find differences between the oxygen loaded HEA and a usual one.
Only STEM bright field and atom probe tomography revealed the main reason for the spectacular increase in strength: the oxygen is located at interstitial positions within agglomerations of lighter atom , i.e. Ti and Zr.
“We could reveal that the oxygen locates within zones containing only a handful of atoms that are enriched in Ti, and, to a lesser extent Zr. Within these zones, the oxygen is arranged in a highly ordered manner forming individual trapping barriers. At the same time the ductility is increased during deformation when these ordered complexes are cut by dislocations, which are the crystalline defect that carry the plasticity, and cause their multiplication and change the way they shear the crystalline lattice.”, explains Dr. Baptiste Gault, head of the “Atom Probe Tomography” group at the MPIE. The oxygen complexes act as small precipitates and cause a change from planar to wavy slip during deformation.
The presented alloy is a model system, exhibiting too little oxidation resistance. Research to improve their performance by adding Al, Si or Cr is ongoing. The interstitial complex strengthening mechanism could be forming in many other alloy classes beyond HEAs. The scientists are exploring other metallic systems in which the strengthening effects from these ordered complexes could be exploited, in particular alloys that are closer to engineering applications. The work was funded by the Natural Science Foundation of China.
Dr. Baptiste Gault, email@example.com
Z. Lei, X. Liu, Yua. Wu, H. Wang, S. Jiang, S. Wang, X. Hui, Y. Wu, B. Gault, P. Kontis, D. Raabe, L. Gu, Q. Zhang, H. Chen, H. Wang, J. Liu, K. An, Q. Zeng, T. Nieh, Z. Lu
Enhanced strength and ductility in a high-entropy alloy via ordered oxygen complexes
Nature 563 (2018)
Yasmin Ahmed Salem M.A. | Max-Planck-Institut für Eisenforschung GmbH
Topological material switched off and on for the first time
11.12.2018 | ARC Centre of Excellence in Future Low-Energy Electronics Technologies
Proteins imaged in graphene liquid cell have higher radiation tolerance
10.12.2018 | INM - Leibniz-Institut für Neue Materialien gGmbH
A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.
The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...
A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.
Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...
Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...
What if a sensor sensing a thing could be part of the thing itself? Rice University engineers believe they have a two-dimensional solution to do just that.
Rice engineers led by materials scientists Pulickel Ajayan and Jun Lou have developed a method to make atom-flat sensors that seamlessly integrate with devices...
Scientists at the University of Stuttgart and the Karlsruhe Institute of Technology (KIT) succeed in important further development on the way to quantum Computers.
Quantum computers one day should be able to solve certain computing problems much faster than a classical computer. One of the most promising approaches is...
10.12.2018 | Event News
06.12.2018 | Event News
03.12.2018 | Event News
12.12.2018 | Life Sciences
12.12.2018 | Life Sciences
12.12.2018 | Health and Medicine