The industrial partners in MMTECH chose a number of case study parts where the use of gamma titanium aluminides would lead to significant weight savings or performance improvements. Comparing the manufacture of the case-studies with the state-of-the-art allows MMTECH technologies to be assessed from a technical, financial and environmental point of view. The material properties, performance specifications and geometrical tolerances for the parts were analysed and used to define the test component geometries. The alloy formulation for the powders developed by MBN was determined based on this analysis, aiming for enhanced workability, creep strength and resistance to oxidisation at high temperatures.
The case study part chosen by AML is a generic turbine blade, such as those found in aircraft engines. Blades for the high-pressure compressor are typically made from nickel alloys. Gamma titanium aluminides are lighter than nickel, so could usefully replace this material without loss of performance. A simplified, generic blade was made in the project to validate the different technologies. Validation was through destructive assessment of sub-surface metallurgical condition. Adaptive machining was used to find the best-fit on the stock parts then adaptive finish machining was employed. There was an 11% reduction in cycle time, a 40% reduction in surface roughness and a 44% improvement in sub-surface quality.
EFESTO is developing components for a range extender unit for electric aircraft. Again, manufacturing parts of this component from gamma titanium aluminide would offer significant weight savings and the ability to use additive manufacturing will lead to an improved design and performance. Within the project, an turbo-impeller was machined and tested. Compared to the original part, there was a weight reduction of 48% and reduced vibration during operation. Overall, there was a reduction in manufacturing steps and manufacturing time.
DIGRO's case study part is an exhaust manifold flange, which is currently made from stainless steel and so has limited dynamic performance. The flange was separted into smaller subparts to manage the thermal distortion. The smaller flanges were made using the laser-cutting machine developed by PRIMA. A second version was machined for comparison, and a desk-top study was carried out to determine the business case for using addtive manufacture (AM) for such a part. When compared to the state of the art, AM reduced the production time by 85%, and laser-cutting reduced it by 64%. AM would also reduce production costs by 89%, similar to the 82% reduction seen from laser cutting. The different parts were tested on a lab car at extremes of temperature and pressure. The parts were stable up to 1,280 degrees.