A research team at the Department of Energy’s Pacific Northwest National Laboratory (PNNL) has developed a method to efficiently convert aluminum scrap into high-strength metal alloys. The process, known as Solid Phase Alloying, eliminates the need for conventional melting processes and offers a promising way to transform industrial waste into high-value products. The results of the study were published in the journal Nature Communications.
At the core of this method is the processing of aluminum waste, which is transformed into durable alloys by adding precise amounts of metals such as copper, zinc, and magnesium. This transformation is achieved using a patented PNNL technique called Shear Assisted Processing and Extrusion (ShAPE). The process involves a rotating die that generates friction and heat, forming a homogeneous alloy from the starting material in less than five minutes. By contrast, traditional melting and casting methods take several days.
“The novelty of our work here is that by adding a precise amount of metal elements into the mix with aluminum chips as a precursor, you can actually transform it from a low-cost waste to a high-cost product,” said Xiao Li, a PNNL materials scientist and lead author of the research study. “We do this in just a single step, where everything is alloyed in five minutes or less.”
A significant advantage of the method is its energy efficiency. By eliminating the energy-intensive melting process, production costs are reduced, and the environmental footprint is minimized. Furthermore, the resulting alloy exhibits exceptional mechanical properties, being up to 200% stronger than conventionally recycled aluminum. Analysis of the internal structure revealed the formation of Guinier-Preston zones during the ShAPE process, which enhance the alloy’s strength at the atomic level.
“Our ability to upcycle scrap is exciting, but the thing that excites me the most about this research is that solid phase alloying is not just limited to aluminum alloys and junk feedstocks,” said Cindy Powell, the chief science and technology officer for energy and environment at PNNL and a coauthor of this study. “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.”
The researchers emphasize the broad application potential of Solid Phase Alloying. Beyond aluminum, other metals could also be recycled and transformed into new alloys through this process. This approach is particularly promising for 3D printing technologies such as Wire Arc Additive Manufacturing (WAAM), creating opportunities for customized wire alloys.
“It’s difficult to obtain feed wires with customized compositions for wire-based additive manufacturing,” said Li. “Solid phase alloying is a fantastic way to produce tailored alloys with exact compositions such as 2 percent copper or 5 percent copper.”
The project was supported by the Solid Phase Processing Science Initiative laboratory program. The researchers view their work as a milestone for resource-efficient recycling and the development of new material solutions.
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