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Large-Scale Materials Modeling at Quantum Accuracy: Ab Initio Simulations of Quasicrystals and Interacting Extended Defects in Metallic Alloys
Ab initio electronic-structure has remained dichotomous between achievable accuracy and length-scale. Quantum many-body (QMB) methods realize quantum accuracy but fail to scale. Density functional theory (DFT) scales favorably but remains far from quantum accuracy. We present a framework that breaks this dichotomy by use of three interconnected modules: (i) invDFT: a methodological advance in inverse DFT linking QMB methods to DFT; (ii) MLXC: a machine-learned density functional trained with invDFT data, commensurate with quantum accuracy; (iii) DFT-FE-MLXC: an adaptive higher-order spectral finite-element (FE) based DFT implementation that integrates MLXC with efficient solver strategies and HPC innovations in FE-specific dense linear algebra, mixed-precision algorithms, and asynchronous compute-communication. Furthermore, we demonstrate a paradigm shift in DFT that not only provides an accuracy commensurate with QMB methods in ground-state energies, but also attains an unprecedented performance of 659.7 PFLOPS (43.1% peak FP64 performance) on 619,124 electrons using 8,000 GPU nodes of Frontier supercomputer.
An Initial Assessment of the Creep-Rupture Strengths for Weldments with Alloy 800H Base Metal and Alloy 617 Filler Metal
The expected minimum stress-to-rupture of the weld is a function of the stress rupture factor (R) and the expected minimum stress-to-rupture (Sr) of the base metal.
Microstructural Responses of Alloy 625 and Alloy 625 Plus Under Ion and Proton Irradiations
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Tunability of martensitic transformation in Mg-Sc shape memory alloys: A DFT study
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Heterogeneity and inelasticity of deformation in a notched martensitic NiTi shape memory alloy specimen
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In-situ high energy X-ray diffraction study of the elastic response of a metastable β-titanium alloy
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H-phase precipitation and its effects on martensitic transformation in NiTi-Hf high-temperature shape memory alloys
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Ultra-fine-grained and gradient FeCrAl alloys with outstanding work hardening capability
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Thermodynamics and design of nanocrystalline alloys using grain boundary segregation spectra
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Atomic origin of CO2-promoted oxidation dynamics of chromia-forming alloys
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Non-linear temperature dependences of pseudoelastic stress and stress hysteresis of a nanocrystalline Ni47Ti50Fe3 alloy
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Electronic structure and dynamics analysis of the Cu-Ag binary alloy by a tight-binding parametrization
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A microstructure-based modeling approach to predict the mechanical properties of Zr alloy with hydride precipitates
In nuclear reactors, hydrides can form in fuel cladding due to hydrogen absorption in ZIrcaloy and cause embrittlement. This work presents a microstructure-based finite element model to predict the stress-strain response of Zircaloy containing hydrides. Quantitative microstructural details extracted from scanning electron microscopy (SEM) images were used to generate heterogeneous microstructures including the morphology and spatial distribution of hydrides. The constitutive material model for zircaloy in this study is based on crystal plasticity theory which considers the hexagonal close-packed (HCP) atomic structure of Zircaloy material. The hydrides were modeled as brittle material along with a damage model. Hydride formation inside the zircoloy matrix results in residual stress. This phenomenon is also captured in this model. A parametric study has been conducted to understand the effect of volume fraction, orientation, and lamellae thickness of the hydride phase on the mechanical properties of the overall material.