Interfacial melting as a thermodynamic indicator of solid-state synthesizability
Abstract
Computational materials discovery commonly ranks candidate materials by their thermodynamic stability on the formation energy convex hull, yet many predicted-stable phases resist synthesis. We propose that solid-state synthesizability through interfacial-melt-mediated routes requires an additional thermodynamic condition: the interfacial melt at the target composition must itself remain locally stable against spinodal decomposition. We examine this in the classical Fe--B system, where thermodynamically stable FeB4 has been reported under high-pressure synthesis but not in low-pressure synthesis attempts. Using melt--quench molecular dynamics driven by a fine-tuned machine-learning interatomic potential, we find that, at ambient pressure, the B-rich interfacial melt near the FeB4 composition develops a concave free-energy landscape, signaling a demixing instability that is corroborated by the concentration--concentration structure factor and correlated with low-energy icosahedral and pentagonal-pyramidal boron motifs. In contrast to FeB4, metastable Fe3B and Fe23B6 remain synthesizable because their corresponding melts are stable. Applied pressure introduces a convex PV contribution that strongly suppresses this instability, reducing the curvature at the FeB4 composition to within the uncertainty of our fit at 1800~K, consistent with the experimental synthesis boundary. Comparison with CrB4 further shows that weaker melt instability correlates with easier experimental synthesis. Interfacial-melt stability, which atomistic simulations can assess via the low-k concentration--concentration structure factor, is thus proposed as a practical thermodynamic screening descriptor of synthesizability for AI-assisted materials discovery.
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BibTeX
@misc{zhang2026interfacial,
title = {{Interfacial melting as a thermodynamic indicator of solid-state synthesizability}},
author = {Zihan Zhang and Mengyi Chen and Qianxiao Li and Peichen Zhong},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2606.22885},
eprint = {2606.22885},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.22885},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Interfacial melting as a thermodynamic indicator of solid-state synthesizability
AU - Zihan Zhang
AU - Mengyi Chen
AU - Qianxiao Li
AU - Peichen Zhong
PY - 2026
DA - 2026/09/24
PB - arXiv
DO - 10.48550/arxiv.2606.22885
UR - https://arxiv.org/abs/2606.22885
AB - Computational materials discovery commonly ranks candidate materials by their thermodynamic stability on the formation energy convex hull, yet many predicted-stable phases resist synthesis. We propose that solid-state synthesizability through interfacial-melt-mediated routes requires an additional thermodynamic condition: the interfacial melt at the target composition must itself remain locally stable against spinodal decomposition. We examine this in the classical Fe--B system, where thermodynamically stable FeB_4 has been reported under high-pressure synthesis but not in low-pressure synthesis attempts. Using melt--quench molecular dynamics driven by a fine-tuned machine-learning interatomic potential, we find that, at ambient pressure, the B-rich interfacial melt near the FeB_4 composition develops a concave free-energy landscape, signaling a demixing instability that is corroborated by the concentration--concentration structure factor and correlated with low-energy icosahedral and pentagonal-pyramidal boron motifs. In contrast to FeB_4, metastable Fe_3B and Fe_23B_6 remain synthesizable because their corresponding melts are stable. Applied pressure introduces a convex PV contribution that strongly suppresses this instability, reducing the curvature at the FeB_4 composition to within the uncertainty of our fit at 1800~K, consistent with the experimental synthesis boundary. Comparison with CrB_4 further shows that weaker melt instability correlates with easier experimental synthesis. Interfacial-melt stability, which atomistic simulations can assess via the low-k concentration--concentration structure factor, is thus proposed as a practical thermodynamic screening descriptor of synthesizability for AI-assisted materials discovery.
ER -