Led by Professors Haiyan Wang and Xinghang Zhang, the team incorporated cobalt, iron, nickel, and titanium into aluminum, creating nanoscale, laminated, deformable intermetallics. Graduate student Anyu Shang is also part of the team.
“Our work shows that the proper introduction of heterogenous microstructures and nanoscale medium-entropy intermetallics offers an alternative solution to design ultrastrong, deformable aluminum alloys via additive manufacturing,” Zhang said. “These alloys improve upon traditional ones that are either ultrastrong or highly deformable, but not both.”
This innovation has been disclosed to the Purdue Innovates Office of Technology Commercialization, which is pursuing a patent.
The findings, supported by the National Science Foundation and the U.S. Office of Naval Research, are published in Nature Communications.
Challenges with Traditional Aluminum Alloys
Lightweight, high-strength aluminum alloys are used in industries from aerospace to automobile manufacturing.
“However, most commercially available high-strength aluminum alloys cannot be used in additive manufacturing,” Shang said. “They are highly susceptible to hot cracking, which creates defects that could lead to the deterioration of a metal alloy.”
A traditional method to alleviate hot cracking during additive manufacturing is the introduction of particles that strengthen aluminum alloys by impeding the movements of dislocations.
“But the highest strength these alloys achieve is in the range of 300 to 500 megapascals, which is much lower than what steels can achieve, typically 600 to 1,000 megapascals,” Wang said. “There has been limited success in producing high-strength aluminum alloys that also display beneficial large plastic deformability.”
Purdue’s Method and Validation
The Purdue researchers have produced intermetallics-strengthened additive aluminum alloys by using several transition metals including cobalt, iron, nickel and titanium. Shang said these metals traditionally have been largely avoided in the manufacture of aluminum alloys.
“These intermetallics have crystal structures with low symmetry and are known to be brittle at room temperature,” Shang said. “But our method forms the transitional metal elements into colonies of nanoscale, intermetallics lamellae that aggregate into fine rosettes. The nanolaminated rosettes can largely suppress the brittle nature of intermetallics.”
Wang said, “Also, the heterogeneous microstructures contain hard nanoscale intermetallics and a coarse-grain aluminum matrix, which induces significant back stress that can improve the work hardening ability of metallic materials. Additive manufacturing using a laser can enable rapid melting and quenching and thus introduce nanoscale intermetallics and their nanolaminates.”
The research team has conducted macroscale compression tests, micropillar compression tests and post-deformation analysis on the Purdue-created aluminum alloys.
“During the macroscale tests, the alloys revealed a combination of prominent plastic deformability and high strength, more than 900 megapascals. The micropillar tests displayed significant back stress in all regions, and certain regions had flow stresses exceeding a gigapascal,” Shang said. “Post-deformation analyses revealed that, in addition to abundant dislocation activities in the aluminum alloy matrix, complex dislocation structures and stacking faults formed in monoclinic Al9Co2-type brittle intermetallics.”
Purdue University professor Xinghang Zhang (right) and graduate research assistant Anyu Shang prepare to use a 3D printer at the Flex Lab in Discovery Park District at Purdue. Zhang and Haiyan Wang, Purdue’s Basil S. Turner Professor of Engineering, have developed a method to create ultrahigh-strength aluminum alloys that also demonstrate high plastic deformability. Their research has been published in Nature Communications. (Purdue University photo/Huan Li)
More Information
The Purdue Innovates Office of Technology Commercialization supports Purdue University’s economic development initiatives by commercializing, licensing, and protecting intellectual property. In fiscal year 2023, the office finalized 150 deals, signed 203 technologies, received 400 disclosures, and was issued 218 U.S. patents. The Purdue Research Foundation, which manages the office, received the 2019 Innovation & Economic Prosperity Universities Award for Place and was ranked third nationally in startup creation by IPWatchdog Institute in 2020.
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Shang, A., Stegman, B., Choy, K. et al. (2024) Additive manufacturing of an ultrastrong, deformable Al alloy with nanoscale intermetallics. Nat Commun 15, 5122 (2024). doi.org/10.1038/s41467-024-48693-4
