Theory-guided design of duplex-phase multi-principal-element alloys

• DOI: 10.1016/j.actamat.2024.119952
• Publication Date: 2024-04-22T12:38:01Z
• Authors: Prashant Singh; Duane D. Johnson; Jordan Tiarks; Emma M.H. White; Andrew B. Kustas; Jonathan W. Pegues; Morgan R. Jones; Hannah Lim; Frank W. DelRio; Jay D. Carroll; Gaoyuan Ouyang; Michael J. Abere; Rameshwari Naorem; Hailong Huang; Trevor M. Riedemann; Paul G. Kotula; Iver E. Anderson; Nicolas Argibay
• Keywords: High-Entropy Alloys

Density-functional theory (DFT) is used to identify phase-equilibria in multi-principal-element and high-entropy alloys (MPEAs/HEAs), including duplex-phase and eutectic microstructures. A combination of composition-dependent formation energy and electronic-structure-based ordering parameters were used to identify a transition from FCC to BCC favoring mixtures, and these predictions experimentally validated in the Al-Co-Cr-Cu-Fe-Ni system. A sharp crossover in lattice structure and dual-phase stability as a function of composition were predicted via DFT and validated experimentally. The impact of solidification kinetics and thermodynamic stability was explored experimentally using a range of techniques, from slow (castings) to rapid (laser remelting), which showed a decoupling of phase fraction from thermal history, i.e., phase fraction was found to be solidification rate-independent, enabling tuning of a multi-modal cell and grain size ranging from nanoscale through macroscale. Strength and ductility tradeoffs for select processing parameters were investigated via uniaxial tension and small-punch testing on specimens manufactured via powder-based additive manufacturing (directed-energy deposition). This work establishes a pathway for design and optimization of next-generation multiphase superalloys via tailoring of structural and chemical ordering in concentrated solid solutions. ; This is a manuscript of the article published as Singh, Prashant, Duane D. Johnson, Jordan Tiarks, Emma MH White, Andrew B. Kustas, Jonathan W. Pegues, Morgan R. Jones et al. "Theory-guided design of duplex-phase multi-principal-element alloys." Acta Materialia 272 (2024): 119952. doi: https://doi.org/10.1016/j.actamat.2024.119952.