A new process enables aluminum alloys for 3D printing that are not only high-strength but also highly formable. Until now, it was either or.
Researchers at Purdue University are producing ultra-strong aluminum alloys for additive manufacturing.
Purdue University photo/Huan Li
An engineering team at Purdue University in the US state of Indiana has developed a process for high-strength aluminum alloys that are suitable for additive manufacturing due to their plastic deformability. Specifically, intermetallically strengthened additive aluminum alloys were produced using various transition metals such as cobalt, iron, nickel and titanium.
"Our work shows that heterogeneous microstructures and medium entropy nanoscale intermetallics offer an alternative solution for developing high-strength, highly formable aluminum alloys through additive manufacturing," said Xinghang Zhang, one of the leaders of the research team. "These alloys are better than conventional ones, which are either high-strength or highly formable, but not both."
Aluminum Alloys Prone to Hot Cracking
According to the researchers, most commercially available high-strength aluminum alloys cannot be used for additive manufacturing. The reason: they are susceptible to hot cracking. A traditional method of reducing hot cracking in additive manufacturing is the introduction of particles.
But there is a problem: the highest strength that these alloys achieve is in the range of 300 to 500 MPa. Steels, on the other hand, typically reach 600 to 1000 MPa. Until now, there has only been limited success in producing high-strength aluminum alloys that also exhibit corresponding plastic deformability.
Intermetallic Lamellae on the Nanoscale
PhD student Anyu Shang explains: "Our method forms the transition metal elements into colonies of intermetallic lamellae on a nanoscale, which assemble into fine rosettes. The nanolaminated rosettes can largely suppress the brittleness of the intermetallics."
Co-study leader Haiyan Wang adds: "In addition, the heterogeneous microstructures contain hard nanoscale intermetallics and a coarse-grained aluminum matrix, which induces significant back stress." This in turn could improve the work hardening of metallic materials.
Publication in Nature Communications
The research team carried out macro-scale compression tests, micropillar compression tests and post-deformation analyses on the aluminum alloys produced. During the macro-scale tests, the alloys showed a combination of pronounced plastic deformability and high strength of more than 900 MPa. The research results were published in the journal Nature Communications.
This is a partly automated translation of this german article.
