The presented study contributes to the development of new alloys for AM processes. The development of the methodology is characterised by a combination of computer-aided and physical alloy screening. The focus is on nickel-based superalloys with a high y'-content, which in some cases have a high solidification interval. As a result, segregation phenomena occur in the manufacturing process, which can lead to hot cracks and should therefore be reduced or avoided completely. By combining physical modelling approaches and computer simulation with experimental process parametrization and extended microstructural analyses, a fundamental understanding of the segregation behaviour of the reference alloy CM247LC in the LPBF process is generated.

The project includes the development of a screening tool to automatically identify possible alloy candidates by thermodynamic calculations (CALPHAD) and compare them using various criteria, such as kou-criterion, creep resistance models, thermal and mechanical properties and so on. An AM-modified version of CM247LC is identified, which is possibly less susceptible to process-induced hot cracking, while having similarly good mechanical properties in the high-temperature range. This AM modification is produced, characterised, and compared to the initial state.

To be able to make a better selection of the calculated alloy candidates, elements critical to hot cracking are identified by combining process and microstructure simulation. The thermal process conditions, which are essential for the simulation of the microstructure (phase field), are calculated by process simulation (FEM). The segregation behaviour is correlated with the energy input, which are mainly dependent on the process parameters. The validation of the results is carried out using data from the experiments as well as the results of comprehensive microstructural investigations (SEM/TEM/HEXRD/APT).

-Project within the DPP Research Campus Aachen