Solid phase manufacturing has the potential to develop custom metal alloys through a revolutionary technique known as solid phase alloying, as indicated by recent research findings.
According to a new study conducted by researchers at the Department of Energy’s Pacific Northwest National Laboratory, metal scrap can be effectively transformed into high-performance, valuable alloys without relying on traditional melting methods.
This research, published in the journal Nature Communications this week, illustrates that scrap aluminum derived from industrial waste can be used to create high-performance metal alloys. The recycled aluminum rivals materials created from virgin aluminum, suggesting that this approach offers a cost-effective solution for increasing the availability of high-quality recycled metal products. By converting waste into durable aluminum goods, the solid phase alloying method not only improves material performance but also promotes environmental sustainability.
“Our research is innovative because we can convert low-cost waste into high-value products by adding specific metal elements to aluminum chips in a single step that takes five minutes or less,” stated Xiao Li, a materials scientist at PNNL and the lead author of the study.
The solid phase alloying technique swiftly transforms aluminum scrap mixed with copper, zinc, and magnesium into a high-strength aluminum alloy within minutes, a significant reduction from the days typically required using conventional processes like melting, casting, and extrusion. The team utilized a patented method named Shear Assisted Processing and Extrusion (ShAPE) to attain these outcomes. They emphasized, however, that their findings should be replicable through other solid phase manufacturing techniques.
In the ShAPE process, high-speed rotating dies generate friction and heat that uniformly blend the initial chunky ingredients into an alloy identical to that of newly-produced aluminum wrought products. This solid-state approach eliminates the energy-demanding bulk melting stage, and when combined with low-cost scrap materials, has the potential to greatly lower manufacturing expenses. Consumers will benefit from recycled aluminum products that offer improved lifespan and performance at reduced costs, whether used in vehicles, construction, or household appliances.
Metal alloy with core strength
The research team employed mechanical tests and sophisticated imaging to assess the microstructure of the upcycled materials obtained through solid phase alloying. Their findings revealed that the ShAPE upcycled alloy develops a unique nanostructure at the atomic scale. During the ShAPE process, atomic-level structures known as Guinier-Preston zones emerge within the alloy, which are recognized for enhancing strength in metal alloys. The upcycled alloy is 200% stronger and exhibits superior ultimate tensile strength compared to conventional recycled aluminum, which could lead to longer-lasting and better-performing products for consumers.
“While our ability to upcycle scrap is thrilling, what excites me most about this research is that solid phase alloying isn’t just confined to aluminum alloys and scrap materials,” said Cindy Powell, PNNL’s chief science and technology officer for energy and environment and a coauthor of the study. “Theoretically, solid phase alloying can be applied to any imaginable metal combination. As this processing happens entirely in a solid state, it opens doors to create entirely new alloys that we couldn’t make before.”
The solid phase alloying method could potentially be used to manufacture custom metal wire alloys for distinct 3D printing applications, noted Li. For instance, wire arc additive manufacturing (WAAM) is utilized for 3D printing or repairing metal components, where a wire feed is melted by a robotic welding torch to construct 3D parts.
“Obtaining feed wires with tailored compositions for wire-based additive manufacturing is quite challenging,” Li explained. “Solid phase alloying presents an excellent opportunity to produce customized alloys with precise compositions, such as 2% or 5% copper.”
This research was funded by the Laboratory Directed Research and Development program at PNNL within the framework of the Solid Phase Processing Science Initiative. The team also included PNNL researchers Tianhao Wang, Zehao Li, Tingkun Liu, Xiang Wang, Arun Devaraj, Cindy Powell, and Jorge F. dos Santos.
