RESEARCH NEWS
New ‘ designer ’ titanium alloys
A team of researchers has created a new class of strong titanium alloys by integrating alloy and-3D printing process designs . The research , published in Nature magazine , could help extend the applications of titanium alloys , improve sustainability and drive innovative materials technologies .
Titanium and titanium alloys are essential for the clean energy transition , defence and aerospace sectors . The research holds promise for a new class of more sustainable , high-performance titanium alloys for applications in aerospace , biomedical , chemical engineering , space and energy technologies .
The research was led by the University of Sydney and RMIT in collaboration with Hong Kong Polytechnic University and Melbourne company , Hexagon Manufacturing Intelligence .
Co-lead researcher , University of Sydney Pro-Vice-Chancellor ( Research Infrastructure ), Professor Simon Ringer , said : “ 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 .”
Strengthened alloys
The new materials belong to an alloy class that has long been the backbone of the titanium industry . They consist of a mixture of two forms of titanium crystals , called alpha-titanium phase and beta-titanium phase , each corresponding to a specific arrangement of atoms .
While titanium alloys have traditionally been produced by adding aluminium and titanium , the researchers investigated the use of oxygen and iron , abundant and inexpensive elements that can act as powerful stabilisers and strengtheners of alpha- and beta-titanium phases .
“ The critical enabler is the unique distribution of oxygen and iron atoms within and between the alpha-titanium and betatitanium phases ,” said Professor Ringer , an
USyd Atom Probe .
Ma Qian and Tingting Song in front of the laser 3D printer that the team used at RMIT University . Image courtesy of RMIT .
expert in materials science and engineering at the School of Aerospace , Mechanical and Mechatronic Engineering .
“ 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 ( retaining its strength after being moulded into a narrow thread ) allowing us to exert control over the local atomic bonding and so mitigate the potential for embrittlement .”
Lead researcher Distinguished Professor Ma Qian from RMIT said that the team embedded circular economy thinking in their design , creating great promise for producing their new titanium alloys from industrial waste and low-grade materials .
“ Reusing waste and low-quality materials has the potential to add economic value and reduce the high carbon footprint of the titanium industry ,” said Professor Qian from RMIT ’ s Centre for Additive Manufacturing in the School of Engineering .
Overcoming challenges
According to the researchers , two challenges have hindered the development of strong and ductile alpha-beta titaniumoxygen-iron alloys through conventional manufacturing processes .
“ 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 betatitanium ,” said Professor Ma Qian .
The team used Laser Directed Energy Deposition ( L-DED ), a 3D-printing process suitable for making large , complex parts , to print their alloys from metal powder , developing a microstructure to rival commercial
Professor Simon Ringer . alloys .
Lead author Dr . Tingting Song , RMIT Vice-Chancellor ’ s Research Fellow , said : “ 3D printing offers a fundamentally different way of making novel alloys and has distinct advantages over traditional approaches . There ’ s a potential opportunity for industry to reuse waste sponge titanium-oxygen-iron alloy , ‘ out-of-spec ’ recycled high-oxygen titanium powders or titanium powders made from high-oxygen scrap titanium using our approach .”
Co-lead author Dr . Zibin Chen , who joined Hong Kong Polytechnic University from the University of Sydney in the later stages of the collaboration , said the research had broader implications : “ Oxygen embrittlement is a major metallurgical challenge not only for titanium , but also for other important metals such as zirconium , niobium and molybdenum and their alloys . Our work may provide a template to mitigate these oxygen embrittlement issues through 3D printing and microstructure design .”
Professor Ringer said the team ’ s work benefited from sustained , targeted investment in research infrastructure from national and state governments and universities .
The Australia Research Council ( ARC ), through the Discovery Programme and the Training Centre in Surface Engineering for Advanced Materials ( SEAM ), funded and supported this research .
The team acknowledges support from the Australia – U . S . Multidisciplinary University Research Initiative ( AUSMURI ) programme supported by the Australian Government ; The Hong Kong Polytechnic University ; the State Key Laboratories in Hong Kong from the Innovation and Technology Commission of the Government ; and Hexagon Manufacturing Intelligence for its Simufact DED solution used in the L-DED process design . The University of Sydney researchers acknowledge technical and scientific support for atom probe experiments at Sydney Microscopy and Microanalysis ( SMM ). SMM is a foundational node of Microscopy Australia , the NCRIS-supported national microscopy facility .
The team ’ s research paper , ‘ Strong and ductile titanium-oxygen-iron alloys by additive manufacturing ’, is published in Nature ( DOI : 10.1038 / s41586-023-05952-6 ). n
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