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Aviation is one of the fastest-growing sources of greenhouse gas emissions. The industry has a significant impact on the environment, with direct emissions from aviation accounting for about 3% of the EU’s total greenhouse gas emissions and more than 2% of global emissions. One possible solution is to develop lighter materials for component parts, leading to reduced fuel consumption and CO2 production.
Bringing together leading research institutions and industrial partners, the MMTech project is focusing on enabling more efficient production of aircraft components made from one particularly promising lightweight metal alloy: gamma titanium aluminides (γ-TiA).
These alloys have long been recognised by the aerospace industry as promising materials due to their low density, light weight and high strength at elevated temperatures. But manufacturing components from γ-TiAl alloys poses significant challenges.
“Gamma titanium aluminides are used in industry today, but there is not much take-up because they are very hard to work with and brittle at room temperature, making them an expensive choice,” says MMTech coordinator Rosemary Gault from the University of Sheffield in the UK. “The aim of MMTech is to lower the cost of manufacturing with γ-TiAl, both by reducing the amount of raw material used and by reducing the number of parts that are scrapped due to production flaws.”
A more attractive option
Achieving that goal could have a big impact on future aircraft, particularly components such as engine turbine blades and other parts exposed to high temperatures. Components made of γ-TiAl weigh about half as much as parts made from nickel-based alloys, while maintaining high specific stiffness and strength.
To increase the appeal of γ-TiAl for manufacturing aircraft components, the MMTech partners are applying novel technologies and techniques across the entire manufacturing chain.
Members of the project consortium are implementing rapid near-net deposition processes to produce components that are close to the desired size and shape, requiring a minimal amount of finishing. This approach reduces material waste but requires careful selection of raw materials.
To address the issue, the partners are developing high-energy ball-milled powders as the raw intermetallic input material. These powders are not only cheaper than other raw forms of γ-TiAl, but their production is being standardised within the project to eliminate variations between batches that can require manufacturing machines to be recalibrated at additional cost.
Innovation in industry
“If we can make gamma titanium aluminides an attractive option for aerospace components, it will give companies a competitive advantage as parts will be lighter, with good performance at high temperatures. As gamma titanium is lighter, plane weight would be reduced and fuel and CO2 savings would be achieved,” Gault says.
The novel manufacturing processes are being supported by other innovations to reduce the risk of damage to the produced components, including using lasers to mitigate cracking and applying self-adaptive control algorithms for machining.
The MMTech academic partners have developed simulation tools to model the entire manufacturing process, enabling virtual testing of the various stages of production to optimise different manufacturing strategies.
Several of the Italian industrial partners involved in MMTech are now planning to apply the innovations in their production lines: MBN Nanomaterialia will commercialise the new powders for use on a range of manufacturing machines, while PRIMA will begin marketing new machine components and FIDIA plans to offer a machine tool that has been optimised for machining γ-TiAl materials.
“The project results will drive future research and consultancy projects with industry, creating opportunities for wider adoption of γ-TiAl in manufacturing for the aviation sector,” Gault says.