Influence of Coherent Elastic Strain on Phase Separation in BCC Nb-V Alloys

Fuente: arXiv
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Auteurs principaux: Zhu, Siya, Arróyave, Raymundo
Format: Preprint
Publié: 2026
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author Zhu, Siya
Arróyave, Raymundo
author_facet Zhu, Siya
Arróyave, Raymundo
contents Coherent elastic strain is an important but often neglected contribution to phase-separation thermodynamics in alloy systems where decomposed phases have appreciable lattice mismatch. We develop a thermodynamic framework that incorporates coherent elastic compatibility directly into phase-diagram calculations alongside conventional CALPHAD chemical free energies. Applied to the BCC Nb-V system, the framework shows that coherent elasticity substantially suppresses phase separation, narrows the miscibility gap, and lowers the critical temperature toward experimentally observed values. Beyond these quantitative effects, the coherent constraint qualitatively alters the interpretation of phase equilibria: the equilibrium decomposition compositions become functions of both temperature and overall alloy composition, so the two-phase boundary no longer represents unique coexistence compositions. These results establish coherent elasticity as a key thermodynamic factor in lattice-mismatched systems and provide a general framework for coherent phase-diagram modeling.
format Preprint
id arxiv_https___arxiv_org_abs_2605_01031
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Influence of Coherent Elastic Strain on Phase Separation in BCC Nb-V Alloys
Zhu, Siya
Arróyave, Raymundo
Materials Science
Coherent elastic strain is an important but often neglected contribution to phase-separation thermodynamics in alloy systems where decomposed phases have appreciable lattice mismatch. We develop a thermodynamic framework that incorporates coherent elastic compatibility directly into phase-diagram calculations alongside conventional CALPHAD chemical free energies. Applied to the BCC Nb-V system, the framework shows that coherent elasticity substantially suppresses phase separation, narrows the miscibility gap, and lowers the critical temperature toward experimentally observed values. Beyond these quantitative effects, the coherent constraint qualitatively alters the interpretation of phase equilibria: the equilibrium decomposition compositions become functions of both temperature and overall alloy composition, so the two-phase boundary no longer represents unique coexistence compositions. These results establish coherent elasticity as a key thermodynamic factor in lattice-mismatched systems and provide a general framework for coherent phase-diagram modeling.
title Influence of Coherent Elastic Strain on Phase Separation in BCC Nb-V Alloys
topic Materials Science
url https://arxiv.org/abs/2605.01031