Scientists use 3D printing to create stronger titanium alloys
The new discovery may lead to applications in aerospace, biomedical, chemical engineering, space and energy technologies.
Scientists have used 3D printing to engineer a new class of titanium alloys that function better under tension. The result is materials that are stronger and less brittle.
This is according to a new press release by RMIT published on Thursday.
The researchers included members from RMIT University and the University of Sydney, in collaboration with Hong Kong Polytechnic University and Hexagon Manufacturing Intelligence in Melbourne.
Lead researcher Distinguished Professor Ma Qian from RMIT told MIT that circular economy thinking was embedded in their new design from the very beginning.
“Reusing waste and low-quality materials has the potential to add economic value and reduce the high carbon footprint of the titanium industry,” said Qian from RMIT’s Centre for Additive Manufacturing in the School of Engineering.
The new titanium alloys comprise two forms of titanium crystals, alpha-titanium phase, and beta-titanium phase, that have been the backbone of the titanium industry.
These alloys have been produced primarily by adding aluminum and vanadium to titanium for years.
Now, the research teams tried using oxygen and iron, which are abundant and inexpensive, to produce the new alloys.
This process was meant to address the two challenges that have hindered the development of strong and ductile alpha-beta titanium-oxygen-iron alloys, Qian explained.
“One challenge is that oxygen – described colloquially as ‘the kryptonite to titanium’ – can make titanium brittle, and the other is that adding iron could lead to serious defects in the form of large patches of beta-titanium.”
A 3D printed process called Laser Directed Energy Deposition (L-DED) was used to produce the new alloys from metal powder.
“A key enabler for us was the combination of our alloy design concepts with 3D-printing process design, which has identified a range of alloys that are strong, ductile and easy to print,” Qian said.
Attractive properties
This resulted in a microstructure of the new alloys that lends itself to many attractive properties.
“This research delivers a new titanium alloy system capable of a wide and tunable range of mechanical properties, high manufacturability, enormous potential for emissions reduction, and insights for materials design in kindred systems,” told RMIT co-lead researcher and the University of Sydney Pro-Vice-Chancellor Professor Simon Ringer.
“The critical enabler is the unique distribution of oxygen and iron atoms within and between the alpha-titanium and beta-titanium phases.
“We’ve engineered a nanoscale gradient of oxygen in the alpha-titanium phase, featuring high-oxygen segments that are strong and low-oxygen segments that are ductile, allowing us to exert control over the local atomic bonding and so mitigate the potential for embrittlement.”
Now, the discovery may lead to applications in aerospace, biomedical, chemical engineering, space, and energy technologies and could help extend the applications of titanium alloys, improve sustainability, and drive innovative alloy design.
The research is published in the journal Nature.
Study abstract:
Titanium alloys are advanced lightweight materials, indispensable for many critical applications. The mainstay of the titanium industry is the α–β titanium alloys, which are formulated through alloying additions that stabilize the α and β phases. Our work focuses on harnessing two of the most powerful stabilizing elements and strengtheners for α–β titanium alloys, oxygen and iron which are readily abundant. However, the embrittling effect of oxygen, described colloquially as ‘the kryptonite to titanium’8, and the microsegregation of iron have hindered their combination for the development of strong and ductile α–β titanium–oxygen–iron alloys. Here we integrate alloy design with additive manufacturing (AM) process design to demonstrate a series of titanium–oxygen–iron compositions that exhibit outstanding tensile properties. We explain the atomic-scale origins of these properties using various characterization techniques. The abundance of oxygen and iron and the process simplicity for net-shape or near-net-shape manufacturing by AM make these α–β titanium–oxygen–iron alloys attractive for a diverse range of applications. Furthermore, they offer promise for industrial-scale use of off-grade sponge titanium or sponge titanium–oxygen–iron10,11, an industrial waste product at present. The economic and environmental potential to reduce the carbon footprint of the energy-intensive sponge titanium production is substantial.
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