Elastic-Contrast Screening and Validation Roadmap for Refractory High-Entropy Alloy/Intermetallic Heterostructures
Year: 2026
Type: preprint
Abstract: Coatings and structural materials intended for service at 1000–1500°C must simultaneously retain mechanical strength, phase stability, oxidation resistance, and interfacial integrity. This work presents a physics-informed design-space prioritisation framework for refractory high-entropy alloy (RHEA)/intermetallic heterostructures. The purpose is not to identify a universally optimal architecture from elastic contrast alone, but to transparently prioritise candidate layer pairs for focused thermodynamic, interfacial, temperature-dependent mechanical, and experimental validation. DFT-derived elastic properties for BCC RHEA special-quasirandom-structure approximants are combined with room-temperature elastic descriptors for B2 NiAl, L1₂ Ni₃Al, and D0₂₂ TiAl₃. For cubic NiAl and Ni₃Al, polycrystalline descriptors are derived by Voigt–Reuss–Hill averaging of reported single-crystal stiffness constants, yielding \(\:{E}_{VRH}=183.6\) GPa and 199.8 GPa, respectively. TiAl₃ is defined as the equilibrium tetragonal D0₂₂ reference phase; its previously compiled \(\:E=183.0\) GPa input is retained as a phase-specific room-temperature screening descriptor. A Young’s-modulus mismatch index, \(\:{k}_{E}\), is used as a first-pass descriptor of elastic contrast relevant to Koehler-type interface-strengthening concepts; it is not treated as a direct prediction of multilayer hardness, interface strength, or high-temperature service performance. Within the primary reference set, Cr–Mo–W–Re/D0₂₂-TiAl₃ exhibits the largest present \(\:{k}_{E}\) value, 0.333, closely followed by Cr–Mo–W–Re/B2-NiAl, 0.331. Ta–Mo–W–Re/B2-NiAl, with \(\:{k}_{E}=0.302\), is retained as a technologically established B2 benchmark. Al₃Zr₅-containing pairs are excluded from the quantitative ranking and retained only as separate high-risk/high-reward prospective hypotheses. The framework distinguishes elastic screening from final performance prediction and defines a validation sequence covering phase stability, reaction thermodynamics, diffusion kinetics, interface structure and adhesion, thermal-expansion compatibility, oxidation behaviour, and thermomechanical response.
Source: Research Square
Author: Hafid Aourag
Language: English
Topic: High Entropy Alloys Studies
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7214971902