Ground-State Structure Search of Defective High-Entropy Alloys Using Machine-Learning Potentials and Monte Carlo Sampling
Revolutionizing HEA Structure Prediction with PAIPAI: AI-Driven Efficiency for Complex Materials
This paper introduces PAIPAI, a Monte Carlo framework coupled with machine-learning interatomic potentials (MLIPs) for predicting ground-state atomic configurations in defective high-entropy alloys (HEAs). PAIPAI utilizes a dual-worker architecture for efficient parallel sampling and is demonstrated through case studies on surface segregation, interstitial aggregation, and coupled metallic/interstitial segregation at grain boundaries in HEAs. The framework effectively identifies low-energy configurations, outperforming random sampling, and its MLIP energy rankings are validated against DFT calculations.
Executive Impact
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Deep Analysis & Enterprise Applications
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Computational Framework
PAIPAI's novel dual-worker architecture combines MLIPs with Monte Carlo sampling to efficiently explore vast configurational spaces in defective HEAs. It targets ground-state atomic configurations by minimizing total energy and ensures high accuracy through a fast-slow worker coordination.
Surface Segregation
The framework successfully identifies surface segregation patterns in a Ti-V-Cr-Re HEA slab, demonstrating that certain elements preferentially accumulate at free surfaces to reduce total energy. Monte Carlo optimized structures are significantly lower in energy than randomly sampled ones.
Interstitial Aggregation
PAIPAI reveals that interstitial oxygen and boron atoms aggregate in bulk BCC Nb-Ti-Ta-Hf HEA, preferentially in Hf and Ti-rich environments. This highlights the framework's ability to model interstitial behavior and estimate solubility.
Grain Boundary Segregation
The study demonstrates coupled metallic and interstitial segregation at grain boundaries in Nb-Ti-Ta-Hf, showing that Hf/Ti-enriched regions provide favorable environments for B interstitials, thereby facilitating co-segregation. This is critical for understanding embrittlement and secondary-phase nucleation in refractory HEAs.
Energy Reduction from PAIPAI Optimization
20 eVPAIPAI achieved an approximate 20 eV total energy reduction in the Ti-V-Cr-Re slab system compared to initial random configurations, demonstrating significant optimization capability.
PAIPAI Dual-Worker Workflow
The PAIPAI framework utilizes a dual-worker architecture to efficiently sample configurational space and identify ground-state atomic configurations in defective HEAs.
| Approach | Key Advantages | Limitations |
|---|---|---|
| PAIPAI Monte Carlo |
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| Random Sampling (with MLIP relaxation) |
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Case Study: Grain Boundary Co-Segregation in Nb-Ti-Ta-Hf
In Nb-Ti-Ta-Hf alloys, PAIPAI revealed a strong cooperative interaction between metallic (Hf/Ti) and interstitial (B) segregation at grain boundaries. Hf and Ti intrinsically prefer grain boundary sites, creating favorable environments that subsequently attract boron interstitials. This combined effect leads to a substantial energy reduction and complex ordering pattern, critical for understanding embrittlement and secondary-phase nucleation in refractory HEAs.
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Your AI Implementation Roadmap
A structured approach to integrating PAIPAI into your R&D workflow, ensuring seamless transition and maximum impact.
Phase 1: MLIP Integration & Calibration
Integrate GRACE-2L-OMAT or other selected MLIPs, and calibrate for specific alloy systems. Establish initial training data sets.
Phase 2: PAIPAI Deployment & Initial Sampling
Deploy PAIPAI framework on HPC, define initial lattice topologies and interstitial sites. Perform preliminary Monte Carlo simulations to screen configurations.
Phase 3: Deep Dive & Defect Analysis
Focus on specific defects (surfaces, grain boundaries) and interstitial species. Refine sampling parameters and analyze segregation/ordering patterns. Validate key findings with DFT.
Phase 4: Property Prediction & Optimization
Utilize identified ground-state structures to predict mechanical, thermal, or chemical properties. Optimize alloy compositions for desired performance.
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