A new alloy composed of 3 metals, chromium, cobalt, and nickel, has become the hardest material with the most fracture-resistant properties ever seen on earth.
Strength, ductility, and toughness are three important properties that determine the durability of a material.
The strength represents the ability of the material to resist damage under the action of external force, and the ductility represents the ability of the material to deform before breaking under force. The above two characteristics constitute the toughness of the material against fracture.
When scientists design new materials, they usually want them to be strong while being malleable or tough, but they often have to choose between the former and the latter.
The team of Lawrence Berkeley National Laboratory in the United States invested in the research of high entropy alloy (HEA) materials and found that the strength of the alloy CrMnFeCoNi.
Ductility also does not affect toughness at liquid nitrogen temperatures, while the alloy’s derivative, CrCoNi, exhibits superior properties.
It exhibits high strength and toughness at low temperatures of about minus 196°C.
In order to test the limit, the team continued to test CrCoNi in a liquid helium temperature environment, and was surprised to find that the toughness of the alloy remained stable at minus 253°C, and the toughness reached 500 MPa-Sqrt(meter),
Silicon has a toughness of 1 in the same unit, aluminum is about 35, and the best steel is about 100, so 500 is an amazing number.
After examining the lattice structure of CrCoNi alloys under external forces using several microscopes.
The researchers found that CrCoNi induces a series of atomic interactions in a specific order to achieve low temperature and high toughness. The defects in the crystal are replaced by the applied force until they form barriers to increase the resistance to external forces.
The final step in the process is the transformation of the crystal structure from cubic to hexagonal.
This material has many potential uses, such as in extreme environments such as outer space.
Man-made objects that can withstand extremely low temperatures, but commercialization of the material is still a long way off.
The new paper has also been published in the journal Science.