New research project High Entropy Alloys

The aim of the R&D project is to develop an innovative high entropy alloy (HEA) with improved wear properties for use in injection moulds and a novel casting process for the production of parts (near-net-shape demonstrator) using investment casting. Work and objectives of the partner NRU:

The development of the casting process is divided into the following work:

 Analysis of the manufacturability and the casting technology fundamentals
Qualification and, if necessary, expansion of the plant technology for processing the HEAs
Initial casting trials with material system based on the results of the completed work packages
Scaling up the process technology to application-relevant scales for melt quantities greater than
one kilogram
Adaptation of the process control to achieve the desired properties of the HEAs
Production of a near-net-shape demonstrator for injection moulding plants

Within the framework of the research project applied for here, a process for the synthesis of high entropy alloys for quantities in the kg range is to be tested and qualified for the first time. A vacuum induction furnace is to be used at NRU GmbH as a solution for the realisation of the melt metallurgical synthesis of high entropy alloys. This procedure is intended to minimise the problematic phenomenon of selective evaporation of individual alloy components during the melting of HEA. Since there is primarily theoretical experience in handling HEAs, a specification for the melting process is to be developed at the beginning of the project.
for the melting process should be developed at the beginning of the project.

In which the requirements for crucible and shell materials are defined and approaches for homogenising the alloy components as well as process and plant parameters are included. In a second step, the plant technology of NRU GmbH is to be modified step by step and qualified in preliminary tests. Important points here are the adaptation of the induction coil and the process conditions during the melting and casting process. Subsequently, the melting routine (e.g. addition of the individual elements, melting times, homogenisation time) is to be worked out in initial casting trials with very small quantities.
homogenisation time) will be worked out and Hegel and shell material as well as performance curves and frequency bands will be tested. Samples for tests at the Fraunhofer IWS will also be produced.

For the scaling up of the process technology for quantities larger than one kilogram, a sample geometry must be developed in a further work package. With the help of Design of Experiment (D0E), the melting routine is to be worked out by NRU GmbH. The focus here is on minimising the evaporation of low-melting components and the segregation of individual components. In addition, the materials used must be optimised, especially for casting. In addition, the unpacking and shrinkage behaviour of the alloys as well as the mechanical processing of the cast samples are to be considered. Further systematic and particularly extensive investigations are planned to achieve the desired properties of the HEAs. With a
DoE, parameters such as induction field. Temperature control in the melt and the specific atmosphere are to be investigated with the aim of achieving the smallest possible grain size of the alloy structure.

Loop tests between NRU GmbH and the Fraunhofer IWS are planned to derive the optimised process parameters. A further
Another focus of investigation is the cooling conditions of the cast alloy depending on the specific atmosphere and the realisable cooling rate (air temperature, volume flow, use of additional cooling media). It is important to achieve a reproducible process window through statistical test and result validation. For the production of the near-net-shape demonstrator following the determination of the process parameters, the direction-dependent scaling factors of the high-entropy alloy must be determined and a design suitable for casting must be made.