With new manufacturing techniques, it is possible to create completely new metal alloys with a huge range of possible properties. A team of researchers has just developed a new 3D printable alloy with a specific nanostructure that makes it ultra-strong and ductile.
Most common alloys, such as stainless steel or bronze, are made with a primary metal mixed with smaller amounts of other elements. But an emerging class of materials known as high-entropy alloys (HEAs) involves the mixing of five different elements in roughly equal proportions. The resulting alloys end up with intriguing and useful properties, such as high strength-to-weight ratios and stiffness that increases with temperature.
The new study focuses on an HEA containing equal parts aluminum, cobalt, chromium, iron and nickel. This particular blend has been experimented with for a few years now, but the team achieved it using a technique that hadn’t been applied to it before: laser powder bed fusion. Essentially, the powdered forms of the original metals are laid out on a surface and then blasted with a high-powered laser which causes them to quickly melt and resolidify.
This technique, a form of 3D printing, gives the final alloy a microstructure very different from that obtained with other manufacturing methods. The team describes it as net-like, with alternating layers of different cubic crystal structures. This gives HEA a yield strength of about 1.3 gigapascals, almost three times stronger than when made using conventional casting methods. At the same time, it’s also more ductile, countering a common compromise.
“The atomic rearrangement of this unusual microstructure gives rise to ultra-high strength as well as enhanced ductility, which is rare because generally solid materials tend to be brittle,” said Wen Chen, principal investigator of the study. “For many applications, a combination of strength and ductility is essential. Our discoveries are original and exciting for materials science and engineering.
This specific combination of strength and ductility could make this alloy useful for components in aerospace, energy, transportation or other engineering fields.
The research was published in the journal Nature.
Source: Georgia Technology