Robert Ritchie / Berkeley Lab
Microscopy images show the path of a fracture and the deformation of the accompanying crystal structure in the nanometer-scale CrCoNi alloy during tension testing at 20 kelvin (-424 F). The fracture propagates from left to right.
According to the researchers, an alloy of chromium, cobalt and nickel not only presents unusual resistance, but also remarkable ductility — the ability to undergo plastic deformation without rupture or cracking.
A team of researchers from Berkeley Lab and Oak Ridge National Laboratory identified the CrCoNian alloy of chromium, cobalt and nickel, as the strongest material known to date.
This discovery, presented in a published in the journal Science, is notable for the unique properties of the material, which combines exceptional hardness with a remarkable ductility — the ability of a material to undergo plastic deformation without fracturing or splitting.
Furthermore, your behavior improves drastically when subject to extremely low temperaturesmaking it an ideal candidate for applications in extreme environments such as space exploration.
CrCoNi belongs to the group of high entropy leagues (HEA)a category characterized by the mixture of elements in equal proportions, which gives the materials a series of unique properties.
This league is capable of withstand severe deformation without fracturingreaching a hardness of 500 megapascals/m2 at temperatures close to liquid helium (-253 °C). By comparison, the traditional materials such as aluminum or the best steels only reach 35 or 100 megapascals/m2respectively.
The study shows that the internal structure of CrCoNi evolves when subjected to deformation, generating mechanisms that increase its resistance.
These properties were analyzed using advanced techniques, such as electron microscopy and neutron diffractionwhich allowed researchers to understand the behavior of the material under extreme conditions.
“When designing structural materials, you want them to be strong, but also ductile and resistant to fracture,” he explains. Easo Georgeresearcher at Oak Ridge National Laboratory and co-author of the study, in one of the laboratory.
O CrCoNi combines these characteristics in an exceptional waywhich distinguishes it from traditional materials, adds the researcher.
The discovery of the characteristics of this alloy may force the materials science community to reconsider long-existing notions about how physical characteristics give rise to performance.
“It’s funny because metallurgists say that the structure of a material defines its properties, but the structure of CrCoNi is the simplest you can imagine — are just grains“, says in turn Robert Ritchieprofessor at the University of California and corresponding author of the study.
“However, when we deform it, the structure becomes very complicated and this change helps explain its exceptional fracture resistance,” adds co-author Andrew Minoralso a researcher at Lawrence Berkeley National Laboratory and professor at the University of California at Berkeley.
The new alloy promises to have a wide spectrum of practical applications in the future. However, the Large-scale production of CrCoNi faces several challenges: The alloy is expensive and complex to manufacture, making it difficult to adopt in everyday applications.
Despite this, researchers believe that it could be fundamental in sectors that require materials capable of withstanding extreme conditionssuch as the low temperatures of deep space or certain industrial environments.
