Multi-scale modelling framework predicts mechanical responses of Fe–Cr–Al alloys across composition and processing conditions

(Press-News.org) A new study published in AI Materials presents a comprehensive multi-scale computational framework capable of predicting the mechanical responses of Fe–Cr–Al alloys while incorporating both solid-solution effects and processing-induced microstructural evolution. By coupling Molecular Dynamics (MD), Phase-Field Method (PFM), and Finite Element Method (FEM) through a temperature-dependent crystal plasticity model, the work provides a pathway for quantitatively linking composition, microstructure, and mechanical performance within the broader context of the Materials Genome Initiative.

Why This Matters Fe–Cr–Al alloys are among the leading candidates for accident-tolerant fuel cladding, yet their application is limited by the difficulty of accurately controlling yield strength and tensile behavior across different temperatures and processing routes. Conventional experimental approaches struggle to capture the full structure–property–process relationship. A scalable multi-scale modelling strategy that can reproduce key deformation mechanisms and microstructural evolution is therefore essential for advancing alloy design, particularly for nuclear-grade materials where reliability is critical.

About the Study The authors developed a bidirectionally calibrated modelling framework that integrates atomic-scale defect mechanics, mesoscale grain evolution, and macroscale mechanical responses. Key components include:

A temperature-dependent critical resolved shear stress (CRSS) model, capturing the relative contributions of solute strengthening, grain boundary hardening, and work-hardening effects.

MD simulations to quantify solute–dislocation interactions, grain-boundary energies, and plastic work in single crystals.

PFM coupled with FFT-based crystal plasticity to simulate rolling, recovery, and recrystallization processes and to generate realistic polycrystalline morphologies.

CPFEM implementation in FEM, including a damage evolution model for predicting stress–strain behavior, yield strength, and ultimate tensile strength.

The model is calibrated using a combination of MD-derived parameters, phase-field simulations, and limited experimental stress–strain data.

Key Findings Consistent reproduction of stress–strain curves: The multi-scale simulations accurately capture the mechanical responses of Fe–Cr–Al samples subjected to different annealing treatments, aligning closely with experimental measurements.

Accurate yield strength predictions across temperatures: The model reproduces the characteristic three-stage temperature-dependent yield strength evolution observed in Fe–Cr–Al alloys, matching literature data across multiple alloy grades.

Atomistically informed solute strengthening: MD-derived interaction energies for Cr, Al, Mo, and Si enable quantitative modelling of screw- and edge-dislocation mechanisms using established strengthening theories.

Realistic microstructure evolution: The framework simulates rolling-induced hardening, recovery behavior, and static recrystallization, producing polycrystalline structures with grain sizes comparable to experimental observations.

Scalable data generation for MGI: The model converts a small set of experiments into hundreds of computational datapoints, enabling machine-learning–based prediction of yield strength with high accuracy (correlation coefficient R = 0.999).

Implications This study demonstrates a robust methodology for predicting mechanical behavior in multi-component Fe-based alloys. By linking composition, temperature, and processing history through physically based models, it provides a tool for high-throughput property prediction and alloy optimization. The approach supports the Materials Genome Initiative by enabling computational exploration of design spaces that would be prohibitively costly to sample experimentally.

Article Information Authors: Zhen Liu, Yaolin Guo, Jingyu Zhang, Yifan Li, Zheyu Hu, Muhammad Adnan, Nianxiang Qiu, Shurong Ding*, and Shiyu Du*.
Title: Multi-scale modelling of mechanical responses of FeCrAl alloys with solid-solution and processing effects
AI Materials, 2025(2):0015. https://doi.org/10.55092/aimat20250015

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