Development of metal matrix composites based on nickel-based superalloys with high creep strength

With the aim of providing lighter and more durable materials for aircraft turbine blades, this research programme proposes the use of innovative metal matrix composites. By combining conventional nickel-based superalloys with titanium carbides in particulate form, materials with superior creep strength can be produced. These are then characterised using techniques such as SEM, EBSD, XRD and TEM, as well as through mechanical tensile and compressive creep tests at temperatures between 600 and 800 °C. The phases are identified, quantified and analysed in detail to establish correlations between microstructure and mechanical behaviour. Finally, the composites with the best performance are identified as candidates for application, as they have the potential to increase the turbine’s performance and efficiency.

Project lead: Dr.-Ing. Georges Lemos

In the field of assembly and interconnection technology for microelectronic systems, increasing demands for miniaturisation and higher functional density require ever more specialised knowledge of the structure and mechanical properties of the joints between, for example, conductor tracks and electronic components such as chips or resistors. The connections required for this are often created by soldering using lead-free metallic alloy systems. However, as a result of mechanical and thermal stress – induced, for example, by temperature cycles – these alloys can lead to the failure of the solder joint and the electronic component. Their reliability can be significantly influenced by the anisotropic mechanical properties of the solder used and its particle structure, which may undergo dynamic changes over its service life.
The focus of the investigations in this project is therefore on the mechanical characterisation of the creep behaviour and the elastic properties of the widely used solder Sn-Ag3.8-Cu0.7, as well as on advanced methods of microstructural analysis such as SEM, EBSD and XRD.

Project researcher: Benedikt Ernst

Electric vehicles have emerged as a particularly prominent solution in the context of new approaches to shaping the mobility of the future. Electrical steel sheets are used in the construction of traction motors; these serve to guide the magnetic flux in the rotor and stator. The magnetic and mechanical properties of the electrical steel are crucial to the efficiency and power-to-weight ratio of the electric motor and are subject to stringent requirements. Furthermore, thin sheet thicknesses of around 0.25 mm and high rotational speeds during dynamic operation lead to high mechanical stresses in the rotor.

For the design of electrical steel to ensure operational reliability, it is therefore essential to understand the cyclic strength properties of the material and how these are influenced by the manufacturing process. Through close collaboration between experimentally validated material investigations and numerical simulation, the aim is to develop an efficient and reliable method for predicting the service life of stamped electrical steel sheets.Project duration: December 2019 – November 2022 (3 years)

Project lead: Paul Kubaschinski, M.Eng.

As part of my PhD project, ‘High-temperature behaviour of high-performance aluminium alloys for additive manufacturing’, the tried-and-tested AlSi10Mg alloy for laser beam melting is being compared with an established, higher-strength (Scalmalloy®) and a novel, higher-strength (Scancromal®) aluminium alloy. In order to investigate the high-temperature behaviour in greater detail, the alloys are examined for the phases and precipitates
formed following different heat treatments. In particular, the aim is to investigate
and understand the metallurgical processes in order to enhance our understanding of additive manufacturing technology.