Phase-field simulations of solidification microsegregation and homogenization behavior for CoCrNiSi0.15 and CoCrNiSi0.3 medium-entropy alloys
Journal
Materials Today Communications
Journal Volume
47
Start Page
113029
ISSN
2352-4928
Date Issued
2025-07
Author(s)
Abstract
This study investigated the solidification and homogenization behaviors of CoCrNiSix (x = 0.15 and 0.3) medium-entropy alloys (MEAs) produced through vacuum induction melting and ceramic mold casting. The investigation was conducted using a multiscale computational–experimental approach, with a combination of macroscale finite-element modeling and mesoscale phase-field simulations. The required solidification paths and thermophysical parameters of the aforementioned alloys were obtained through calculation of phase diagrams evaluations. A macroscale heat transfer model reasonably reproduced the cooling of CoCrNiSix ingots in a ceramic mold. Moreover, phase-field simulations predicted the secondary dendrite arm spacing to be approximately 110 µm, which aligned closely with experimental measurements. Electron probe microanalysis and X-ray diffraction analysis revealed that considerable Si segregation occurred and dendritic morphologies formed in as-cast CoCrNiSix alloys; in particular, a secondary face-centered cubic phase (FCC#2) formed in CoCrNiSi0.3. Homogenization at 1100°C for 48 h effectively reduced microsegregation. Experiments confirmed that the mesoscale phase-field simulations accurately predicted the solidification segregation of Si between dendrites and the residual segregation of Si after homogenization. Therefore, this study employed phase-field simulations to investigate the effects of homogenization conditions on the dynamics of elemental segregation. According to the simulations, homogenization with dynamic temperature adjustment for 8 h can result in a higher solute homogenization level than that achieved through homogenization at 1100°C for 48 h while avoiding incipient melting. This study demonstrates the feasibility of integrating computational and experimental methods to optimize heat treatment processes for lightweight and industrial-grade MEAs.
Subjects
CALPHAD
Heat transfer
Homogenization
Medium-entropy alloys
Phase field
Solidification microstructure
Publisher
Elsevier BV
Type
journal article