About this Abstract |
| Meeting |
MS&T26: Materials Science & Technology
|
| Symposium
|
Progress in High Entropy Materials: Integrating Experiments, Computation, and Machine Learning
|
| Presentation Title |
Computational Investigation of Thermodynamic Stability in Novel High Entropy MAB Phases Based on the Cr₄AlB₄ Structure |
| Author(s) |
Ushan Asela Adhikarige, Deniz Cakir |
| On-Site Speaker (Planned) |
Ushan Asela Adhikarige |
| Abstract Scope |
High-Entropy-MAB (HE-MAB) phases are an emerging class of layered boride ceramics with potential for high-temperature structural applications, yet their thermodynamic stability mechanisms remain incompletely understood. This study employs density functional theory combined with the special quasirandom structure methodology to investigate stability, electronic structure, and chemical ordering of binary, ternary, and high-entropy Cr-based M₄AlB₄ compositions. Convex hull analysis reveals all three investigated five-element HE-MAB phases achieve thermodynamic stability at 0 K, demonstrating that configurational entropy stabilizes phases metastable in lower-order analogues. Metastable compositions become accessible well below synthesis temperatures, with critical temperatures of 83–663 K. Valence electron concentration shows an optimal stability window of VEC ≈ 5.5–6.0. Atomic size mismatch follows a linear penalty of ΔH ≈ 6.5δ meV/atom, with entropic compensation effective up to δ ≈ 9%. Short-range order and sublattice site preference analyses reveal elemental self-organization provides complementary enthalpic stabilization, establishing a multi-descriptor framework for targeted HE-MAB phase synthesis. |
