This new alloy is up to 10 times stronger than steel and surprisingly flexible

Researchers at Purdue University have developed an alloy that is up to 10 times stronger than steel while also being surprisingly flexible. The alloy, known as CoAl, is an intermetallic made from cobalt and aluminum. Intermetallics are solid materials composed of two or more metallic elements arranged in a highly ordered crystal structure. Their unique atomic organization gives them exceptional strength and resistance to deformation.

However, many intermetallics are extremely brittle, making them difficult to shape into complex components without risking fracture. To address this issue, the Purdue engineers introduced a new technique to combine high strength with substantial plasticity in CoAl intermetallics. Plasticity refers to a material's ability to permanently change shape without cracking or breaking, which is crucial for industrial applications.

Professor Xinghang Zhang, the corresponding author of the study, explains that the key to this breakthrough lies in the framework of amorphous interfaces and preexisting dislocations. These flexible boundaries in the material promote the nucleation of dislocations during deformation, which are microscopic irregularities in a crystal that help it deform under extreme force instead of breaking apart.

The researchers used a novel fabrication method called magnetron sputtering deposition to produce the material. This process involves applying a thin film of alloy vapor to a surface, allowing them to introduce a significant number of dislocations into the CoAl. Traditional metal casting methods, which begin with molten material, are not as effective in introducing dislocations.

The resulting CoAl intermetallic reached a yield strength of 6 gigapascals (GPa), which is approximately six to ten times higher than the yield strength of high-strength structural steel. Despite its extreme strength, the material sustained only 15% of plastic strain under compression at room temperature, demonstrating its remarkable flexibility.

This new alloy has potential applications in various high-performance systems, such as turbine blades for aeroengines, where increased strength and plasticity can improve performance and enable the creation of more sophisticated structures. The researchers believe that this novel approach to manufacturing intermetallics using magnetron sputtering deposition could revolutionize the field.