Segregation-guided alloy design via tailored solidification behavior

Materials Today Advances, vol. 25, pp. 100549

Abstract

This study presents an alloy design perspective guided by elemental segregation during solidification to determine the site-specific chemistry and related local thermodynamic properties of dendritic microstructures. This was accomplished via manipulation of the microsegregation behavior by means of nominal alloy composition and thermal conditions of the solidification processes, including modified cooling rates spanning over six orders of magnitudes using ingot casting, directed energy deposition (DED-LB/M) additive manufacturing (AM) and laser powder bed fusion (PBF-LB/M) AM processes. Our approach was demonstrated by computationally designing a novel Al x Co 25 Fe (50-x) Ni 25 multi-principal element alloy (MPEA) as a model system, employing a combination of CALPHAD, Scheil, and multiphase-field simulations, and by experimentally validating the resulting microstructure evolution. The lower Al content (x = 10.5) was designated to generate a supersaturated single-phase fcc matrix suitable for heat-treatments to trigger local phase transformations. The higher Al content (x = 14.5) was selected to define the size and morphology of dual-phase microstructures by controlling phase nucleation and growth through segregation during solidification. Our results showcased how selective enrichment of the desired elements in interdendritic regions can be employed to induce local phase transformations during solidification or post heat-treatments, while their size can be flexibly controlled by the degree of undercooling during solidification. The suggested segregation-guided design approach can be transferred to other alloy systems, enabling effective tuning of local functional, structural, kinetic, and, as shown in this study, thermodynamic properties of dendritic microstructures by predetermining the nature of the alloy matrix through tailored solidification behavior.

Authors 10

1. Ahmet Turnali corresponding

   Technische Universität Berlin

   Affiliation as printed

   Chair Materials for Additive Manufacturing, TU Berlin, 10623, Berlin, Germany

2. Dilay Kibaroglu

   Technische Universität Berlin

   Affiliation as printed

   Chair Materials for Additive Manufacturing, TU Berlin, 10623, Berlin, Germany

3. Jaqueline Gehlmann Aachen Central Facility for Electron Microscopy

   RWTH Aachen University

   Affiliation as printed

   Central Facility for Electron Microscopy, RWTH Aachen University, 52074, Aachen, Germany

4. Lennart Sayk Aachen Digital Additive Production (DAP)

   RWTH Aachen University

   Affiliation as printed

   Digital Additive Production, RWTH Aachen University, 52072, Aachen, Germany

5. Nicolas J. Peter

   Forschungszentrum Jülich

   Affiliation as printed

   Institute of Energy Materials and Devices (IMD-1), Forschungszentrum Jülich GmbH, 52428, Jülich, Germany

6. Abdel-Rahman El-Sayed Aachen Steel Institute

   RWTH Aachen University

   Affiliation as printed

   Steel Institute, RWTH Aachen University, 52072, Aachen, Germany

7. Mehdi Noori
   Affiliation as printed

   Thermo-Calc Software AB, 16967, Solna, Sweden

8. Tarek Allam

   Forschungszentrum Jülich

   Affiliation as printed

   Institute of Energy Materials and Devices (IMD-1), Forschungszentrum Jülich GmbH, 52428, Jülich, Germany

9. Johannes Henrich Schleifenbaum Aachen Digital Additive Production (DAP)

   RWTH Aachen University

   Affiliation as printed

   Digital Additive Production, RWTH Aachen University, 52072, Aachen, Germany

10. Christian Haase

    Technische Universität Berlin

    Affiliation as printed

    Center for 3D Technologies, TU Berlin, 10623, Berlin, Germany

    Chair Materials for Additive Manufacturing, TU Berlin, 10623, Berlin, Germany