Solid phase alloying can turn metal scrap into high-value alloys

Metal scrap can be directly transformed and upgraded into high-performance, high-value alloys without the need for conventional melting processes, according to a new study published this week in the journal Nature Communications. The study demonstrates that scrap aluminum from industrial waste streams can produce high-performance metal alloys.

The upcycled aluminum performs on par with identical materials produced from primary aluminum, indicating that this approach can provide a low-cost pathway to bringing more high-quality recycled metal products to the marketplace. By converting waste into high-performance aluminum products, the new method, called solid phase alloying, not only enhances material properties but also contributes to environmental sustainability.

The innovative solid phase alloying process converts aluminum scrap blended with copper, zinc and magnesium into a precisely designed high-strength aluminum alloy product in a matter of minutes, compared to the days required to produce the same product utilizing conventional melting, casting and extrusion. The research team used a PNNL-patented technique called Shear Assisted Processing and Extrusion, or ShAPE, to achieve their results. However, the researchers noted that the findings should be reproducible with other solid phase manufacturing processes.

Within the ShAPE process, high-speed rotating die create friction and heat that disperses the chunky starting ingredients into a uniform alloy with the same characteristics as a newly manufactured aluminum wrought product. The solid phase approach eliminates the need for energy-intensive bulk melting, which combined with the low-cost feedstocks originating from scrap, has the potential to sharply reduce the cost of manufacturing these materials. For consumers, this means recycled aluminum products will have a longer lifespan and better performance at a lower cost, whether they are part of a vehicle, a construction material, or a household appliance.

According to the researchers, the solid phase alloying process could be used to create custom metal wire alloys for various 3D printing technologies. “Solid phase alloying is theoretically applicable to any metal combination that you can imagine, and the fact that manufacturing occurs wholly in the solid state means you can begin to consider totally new alloys that we’ve not been able to make before,” Cindy Powell, a researcher at the Pacific Northwest National Laboratory, U.S. and a coauthor of the study said in a release.