Structural materials with good fracture properties at very low temperatures. It is important for fields such as space exploration.
As everyone knows, what is the toughest material on earth?’ that’s ‘Diamond’. It pops out on the top line. Diamond is the hardest known material, but its hardness is usually related to the strength of the material. Diamond is tough and strong.
The University of Bristol has discovered an alloy that is stronger at over -250°C, making it the strongest material ever.
These findings, published in Science, show that the chromium-cobalt-nickel alloy has high fracture toughness at high temperatures. It can be used in extreme environments on Earth and in space. The behavior of this particular combination of metals is due to phase transformation. Therefore, when combined with other sensors, they burst and prevent spread.
Lead author Dr. Dong Liu of the School of Physics at Bristol has discovered a high-entropy chromium-cobalt-nickel alloy with an incredibly high fracture toughness at 20 Kelvin. It can be used as structural or load-bearing components for many potential applications in space and cold regions on Earth and other planets.
This behavior is caused by an unexpected phase transformation in combination with other microstructures. It prevents the formation and spread of cracks. The fracture toughness of this alloy is useful for a range of cryogenic applications.
The study explained: “This is very interesting because most alloys become more brittle as the temperature drops. It refers to the sinking of freedom ships in World War II and the Titanic because the metals lose their ductility at low temperatures.”
The scientist also discovered the mechanisms responsible for the improved strength and toughness. This means that these processes can be used as a design guide for scientists and engineers to design better materials.”
They said again: “Experimentally testing the toughness of this material at 20K was not a trivial endeavor. It took us a few years to design and complete. The success of the experiment was based on our rich experience and strong expertise in testing materials under extreme conditions.”
Their team has a plan to untangle the fundamental causes of the sequence of hardening mechanisms in this material at 20 Kelvin. To do this, they used new experimental and modeling methods. They also want to look at other types of high-entropy alloys to see similar behavior.
This study examined the fracture toughness values of the equiatomic CrCoNi and CrMnFeCoNi alloys at 20 Kelvin (K).
- Dong Liu, Robert O. Ritchie et al. Exceptional fracture toughness of medium- and high-entropy CrCoNi-based alloys at 20 Kelvin. Science. DOI: 10.1126/science.abp80