Acta Materialia最新文献

{"title":"Oxygen-vacancy mediated deterministic domain distribution at the onset of ferroelectricity","authors":"Asaf Hershkovitz ,&nbsp;Elangovan Hemaprabha ,&nbsp;Doaa Khorshid ,&nbsp;Liyang Ma ,&nbsp;Shi Liu ,&nbsp;Shai Cohen ,&nbsp;Yachin Ivry","doi":"10.1016/j.actamat.2025.120738","DOIUrl":"10.1016/j.actamat.2025.120738","url":null,"abstract":"<div><div>Ferroelectric domains are mesoscale structures that mediate between synchronized atomic-scale ion displacements and switchable macroscopic polarization. Here, we evaluated the randomness of the domain distribution at the onset of ferroelectricity. First-principle calculations combined with atomic-scale imaging demonstrate that oxygen vacancies that serve as pinning sites for the ferroic domain walls remain immobile above the Curie temperature. Thus, upon cooling to a ferroelectric state, these oxygen vacancies dictate reproducible domain-wall patterning. Domain-scale imaging with variable-temperature piezoresponse force microscopy confirmed the memory effect, questioning the spontaneity of domain distribution under thermotropic transitions.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120738"},"PeriodicalIF":8.3,"publicationDate":"2025-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142975359","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Oxidation behavior of SiC in dissociated oxygen environments","authors":"Zuozheng Chen ,&nbsp;Liping Liu ,&nbsp;Jian Guo ,&nbsp;Chenran Li ,&nbsp;Jia Yu ,&nbsp;Yan Yin ,&nbsp;Shanggeng Li ,&nbsp;Ke Ren ,&nbsp;Min Yi ,&nbsp;Guolin Wang ,&nbsp;Yiguang Wang","doi":"10.1016/j.actamat.2025.120745","DOIUrl":"10.1016/j.actamat.2025.120745","url":null,"abstract":"<div><div>Dissociated oxygen environments are typically encountered during the hyper-speed flight of vehicles. Silicon carbide (SiC) is a typical material used in the thermal protection systems of hyper-speed vehicles; therefore, its oxidation behavior under dissociated oxygen conditions is crucial to the safety of flights. In this study, a high-frequency plasma wind tunnel was used to generate the dissociated oxygen environments to investigate the oxidation behavior of SiC in such environments. During the experiments, growth of silica (SiO₂) was observed on the surface; however, the thickness of this oxide layer reduced simultaneously. A para-linear curve was used to fit the experimental data to distinguish between the growth and recession processes. By combining molecular dynamics simulations with aerodynamic calculations, it was found that the oxidation of SiC was governed by the diffusion of dissociated oxygen through the channels in the SiO₂ crystal, while the loss of surface SiO₂ was due to its sublimation. These findings establish a theoretical foundation for determining the failure boundaries of SiC materials during hyper-speed flight.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120745"},"PeriodicalIF":8.3,"publicationDate":"2025-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142981471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fundamental microscopic properties as predictors of large-scale quantities of interest: Validation through grain boundary energy trends","authors":"Benjamin A. Jasperson ,&nbsp;Ilia Nikiforov ,&nbsp;Amit Samanta ,&nbsp;Brandon Runnels ,&nbsp;Harley T. Johnson ,&nbsp;Ellad B. Tadmor","doi":"10.1016/j.actamat.2025.120722","DOIUrl":"10.1016/j.actamat.2025.120722","url":null,"abstract":"<div><div>Correlations between fundamental microscopic properties computable from first principles, which we term <em>canonical properties</em>, and complex large-scale quantities of interest (QoIs) provide an avenue to predictive materials discovery. We propose that such correlations can be efficiently discovered through simulations utilizing approximate interatomic potentials (IPs), which serve as an ensemble of “synthetic materials”. As a proof of principle we build a regression model relating canonical properties to the symmetric tilt grain boundary (GB) energy curves in face-centered cubic crystals, characterized by the scaling factor in the universal lattice matching model of Runnels et al. (2016), which we take to be our QoI. Our analysis recovers known correlations of GB energy to other properties and discovers new ones. We also demonstrate, using available density functional theory (DFT) GB energy data, that the regression model constructed from IP data is consistent with DFT results, confirming the assumption that the IPs and DFT belong to same statistical pool and thereby validating the approach. Regression models constructed in this fashion can be used to predict large-scale QoIs based on first-principles data and provide a general method for training IPs for QoIs beyond the scope of first-principles calculations.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120722"},"PeriodicalIF":8.3,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142968396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermal spin-torque heat-assisted magnetic recording","authors":"S. Isogami ,&nbsp;Y. Sasaki ,&nbsp;Y. Fan ,&nbsp;Y. Kubota ,&nbsp;J. Gadbois ,&nbsp;K. Hono ,&nbsp;Y.K. Takahashi","doi":"10.1016/j.actamat.2025.120743","DOIUrl":"10.1016/j.actamat.2025.120743","url":null,"abstract":"<div><div>To achieve higher recording density with lower power consumption than the current heat-assisted magnetic recording (HAMR) for next-generation, a more efficient writing with less laser power would be indispensable. An advanced HAMR concept is developed to address such specification, and the write ability has been demonstrated in multilayer media stacks comprising the core structures of antiferromagnetic MnPt and ferromagnetic FePt layers with the magnetic easy axis oriented perpendicular to the film plane. The concept is based on two distinct switching mechanisms: thermally activated (TA) and spin-transfer-torque (STT) assisted magnetization switching. The latter is driven by an out-of-plane temperature gradient (<em>ΔT</em>) in the MnPt/FePt multilayer which is referred as thermal spin-torque (TST) HAMR media. Pump-probe measurements reveal significant magnetic coercivity (<em>H</em>_c) modulation by <em>ΔT</em> at the local magnetization of the FePt layer. The hybrid mechanism with TA and STT can be separated by sweeping the delay time between the pump and probe laser pulses, and it is found that the STT dominates the mechanism for <em>H</em>_c modulation in the short delay time regime. Furthermore, the modulation of <em>H</em>_c of the FePt layer is demonstrated to be dependent on the magnitude and the direction of steady state <em>ΔT</em>. These results suggest that lower laser power consumption is achievable owing to the contribution of STT assisted switching in the TST-HAMR media.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120743"},"PeriodicalIF":8.3,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142975375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electronic structure, phase formation, and defect distribution in the Ba(Ce,Fe,Acc)O3-δ system","authors":"R. Merkle, M.F. Hoedl, A. Chesnokov, D. Gryaznov, E. Bucher, E.A. Kotomin, W. Sitte, J. Maier","doi":"10.1016/j.actamat.2025.120739","DOIUrl":"https://doi.org/10.1016/j.actamat.2025.120739","url":null,"abstract":"Composites of two perovskites are one possibility to combine protonic and p-type electronic conductivity as required for oxygen electrodes in protonic ceramic electrochemical cells. The BaCeO&lt;sub&gt;3&lt;/sub&gt;-BaFeO&lt;sub&gt;3&lt;/sub&gt; system can be acceptor-doped to increase proton uptake and transport. However, preceding experiments [C. Berger et al., J. Mater. Chem. A 10 (2022) 2474; C. Nader et al., Solid State Ionics 406 (2024) 116474] indicated that the dopants are inhomogeneously distributed between the two phases, which is decisive for hydration ability and proton conductivity of such composites. Here, we use extended density functional theory calculations (DFT+U, Hubbard approach) for a comprehensive characterization of the BaCeO&lt;sub&gt;3&lt;/sub&gt;-BaFeO&lt;sub&gt;3&lt;/sub&gt; system including acceptors. Supercells of various compositions are calculated to derive chemical reaction energies, for example for the transfer of defects between the phases. Two key aspects related to the hydration ability of such materials are: (i) The development of the electronic structure with increasing Fe content in a (hypothetical) single-phase BaCe&lt;sub&gt;1-x&lt;/sub&gt;Fe&lt;sub&gt;x&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; perovskite. (ii) The distribution of acceptors (Ga&lt;sup&gt;3+&lt;/sup&gt;, Sc&lt;sup&gt;3+&lt;/sup&gt;, In&lt;sup&gt;3+&lt;/sup&gt;, Y&lt;sup&gt;3+&lt;/sup&gt;) and oxygen vacancies (&lt;span&gt;&lt;span style=\"\"&gt;&lt;/span&gt;&lt;span data-mathml='&lt;math xmlns=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;msubsup is=\"true\"&gt;&lt;mi mathvariant=\"normal\" is=\"true\"&gt;V&lt;/mi&gt;&lt;mrow is=\"true\"&gt;&lt;mi mathvariant=\"normal\" is=\"true\"&gt;O&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow is=\"true\"&gt;&lt;mo is=\"true\"&gt;&amp;#x2022;&lt;/mo&gt;&lt;mo is=\"true\"&gt;&amp;#x2022;&lt;/mo&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;/math&gt;' role=\"presentation\" style=\"font-size: 90%; display: inline-block; position: relative;\" tabindex=\"0\"&gt;&lt;svg aria-hidden=\"true\" focusable=\"false\" height=\"2.779ex\" role=\"img\" style=\"vertical-align: -1.043ex;\" viewbox=\"0 -747.2 1558.3 1196.3\" width=\"3.619ex\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"&gt;&lt;g fill=\"currentColor\" stroke=\"currentColor\" stroke-width=\"0\" transform=\"matrix(1 0 0 -1 0 0)\"&gt;&lt;g is=\"true\"&gt;&lt;g is=\"true\"&gt;&lt;use xlink:href=\"#MJMAIN-56\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;g is=\"true\" transform=\"translate(750,306)\"&gt;&lt;g is=\"true\"&gt;&lt;use transform=\"scale(0.707)\" xlink:href=\"#MJMAIN-2219\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;g is=\"true\" transform=\"translate(353,0)\"&gt;&lt;use transform=\"scale(0.707)\" xlink:href=\"#MJMAIN-2219\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;/g&gt;&lt;g is=\"true\" transform=\"translate(750,-335)\"&gt;&lt;g is=\"true\"&gt;&lt;use transform=\"scale(0.707)\" xlink:href=\"#MJMAIN-4F\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;/g&gt;&lt;/g&gt;&lt;/g&gt;&lt;/svg&gt;&lt;span role=\"presentation\"&gt;&lt;math xmlns=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;msubsup is=\"true\"&gt;&lt;mi is=\"true\" mathvariant=\"normal\"&gt;V&lt;/mi&gt;&lt;mrow is=\"true\"&gt;&lt;mi is=\"true\" mathvariant=\"normal\"&gt;O&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow is=\"true\"&gt;&lt;mo is=\"true\"&gt;•&lt;/mo&gt;&lt;mo is=\"true\"&gt;•&lt;/mo&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;/math&gt;&lt;/span&gt;&lt;/span&gt;&lt;script type=\"math/mml\"&gt;&lt;math&gt;&lt;msubsup is=\"true\"&gt;&lt;mi mathvariant=\"normal\" is=\"true\"&gt;V&lt;/mi&gt;&lt;mrow is=\"true\"&gt;&lt;mi mathvariant=\"normal\" is=\"true\"&gt;O&lt;/mi&gt;&lt;/mro","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"16 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2025-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142962719","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Acoustic shock wave-induced B1 to B2 phase transition of CdO nanoparticles: Structure-property relationship and its mechanism in thermodynamic aspects","authors":"Sivakumar Aswathappa ,&nbsp;Lidong Dai ,&nbsp;Sahaya Jude Dhas Sathiyadhas ,&nbsp;Cathrin Lims Selvakumar ,&nbsp;Raju Suresh Kumar","doi":"10.1016/j.actamat.2025.120742","DOIUrl":"10.1016/j.actamat.2025.120742","url":null,"abstract":"<div><div>The reversible pressure-induced B1 (NaCl) ↔ B2 (CsCl)-type phase transition is one of the classic models for understanding the general concepts of phase transition. Although several outstanding functional properties have been identified for B2 phase materials under high-pressure conditions, generating a stable B2 phase under ambient conditions is a critical task for device fabrication. Herein, we report a novel B1-B2-type phase transition in cadmium oxide nanoparticles (CdO NPs) by millisecond-low-pressure acoustic shock waves (16.5 MPa and 3173 K) that is highly stable under ambient conditions. Under static high-pressure conditions, the B1-B2 phase transition requires ∼102 GPa, which is reversible. A new thermodynamic mechanism is proposed to explain the B1-B2 transition considering the thermal conductivity, whereby materials with low thermal conductivity undergo significant structural phase transitions under acoustic shocked conditions. Herein, we consider several nanosized materials for structural stability, including B1 (CdO, MgO, NiO), Corundum (α-Fe₂O₃, α-Al₂O₃), layered (graphene, graphite) and nonlayered (TiO₂ (anatase), ZnO (B4) and amorphous carbon) materials, under acoustic shocked conditions, which fall within the proposed mechanism.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120742"},"PeriodicalIF":8.3,"publicationDate":"2025-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142962664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Toward prediction and insight of porosity formation in laser welding: A physics-informed deep learning framework","authors":"Xiangmeng Meng ,&nbsp;Marcel Bachmann ,&nbsp;Fan Yang ,&nbsp;Michael Rethmeier","doi":"10.1016/j.actamat.2025.120740","DOIUrl":"10.1016/j.actamat.2025.120740","url":null,"abstract":"<div><div>The laser welding process is an important manufacturing technology for metallic materials. However, its application is often hindered by the occurrence of porosity defects. By far, an accurate prediction of the porosity defects and an insight into its formation mechanism are still challenging due to the highly nonlinear physics involved. In this paper, we propose a physics-informed deep learning (PIDL) framework by utilizing mechanistic modeling and experimental data to predict the porosity level during laser beam welding of aluminum alloys. With a proper selection of the physical variables (features) concerning the solidification, liquid metal flow, keyhole stability, and weld pool geometry, the PIDL model shows great superiority in predicting the porosity ratio, with a reduction of mean square error by 41 %, in comparison with the conventional DL model trained with welding parameters. Furthermore, the selected variables are fused into dimensionless features with explicit physical meanings to improve the interpretability and extendibility of the PIDL model. Based on a well-trained PIDL model, the hierarchical importance of the physical variables/procedures on the porosity formation is for the first time revealed with the help of the Shapley Additive Explanations analysis. The keyhole ratio is identified as the most influential factor in the porosity formation, followed by the downward flow-driven drag force, which offers a valuable guideline for process optimization and porosity minimization.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120740"},"PeriodicalIF":8.3,"publicationDate":"2025-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142962769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Management of reference data in materials science and engineering exemplified for creep data of a single-crystalline Ni-based superalloy","authors":"L.A. Ávila Calderón ,&nbsp;Y. Shakeel ,&nbsp;A. Gedsun ,&nbsp;M. Forti ,&nbsp;S. Hunke ,&nbsp;Y. Han ,&nbsp;T. Hammerschmidt ,&nbsp;R. Aversa ,&nbsp;J. Olbricht ,&nbsp;M. Chmielowski ,&nbsp;R. Stotzka ,&nbsp;E. Bitzek ,&nbsp;T. Hickel ,&nbsp;B. Skrotzki","doi":"10.1016/j.actamat.2025.120735","DOIUrl":"10.1016/j.actamat.2025.120735","url":null,"abstract":"<div><div>The identification of process-structure-property relationships of materials inevitably requires the combination of research data from different measurements. Therefore, the concepts related to FAIR (findable, accessible, interoperable, reusable) data handling, increasingly reported in literature, are particularly important in the materials science and engineering domain. However, they have not yet been integrated into a single, overarching methodological framework, particularly for reference data. Here, we introduce such a framework. Our concept covers data generation, documentation, handling, storage, sharing, data search and discovery, retrieval, and usage. Furthermore, we prototypically implement it using a real dataset with creep data of a single-crystal CMSX-6 Ni-based superalloy. The presented implementation is traceable and permanently accessible through open repositories. The individual elements considered in the framework ensure the functionality and usability of the data and, thus, the adherence to the FAIR principles. In conjunction with this, we present a definition for reference data of materials. Our definition underlines particularly the importance of a comprehensive documentation, e.g., on material provenance, data processing procedures, and the software and hardware used, including software-specific input parameters, as these details enable data users or independent parties to assess the quality of the datasets and to reuse and reproduce the results. Reference data that is managed according to the proposed framework can be used to advance knowledge in the materials science and engineering domain, e.g., by identifying new process-structure-property relations.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120735"},"PeriodicalIF":8.3,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142961716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rationalising the Role of Microalloying Additions in Blended Precipitation","authors":"Shenghan Su, Loreibelle Abian, Jiehua Li, Philip N.H. Nakashima, Laure Bourgeois, Nikhil V. Medhekar","doi":"10.1016/j.actamat.2025.120710","DOIUrl":"https://doi.org/10.1016/j.actamat.2025.120710","url":null,"abstract":"The precipitation of <span><math><msup is=\"true\"><mi is=\"true\">θ</mi><mo is=\"true\">′</mo></msup></math></span> (Al₂Cu) in Al-Cu alloys is greatly influenced by microalloying elements. Combining high-resolution scanning transmission electron microscopy (STEM) with density functional theory (DFT) and classical nucleation theory (CNT) calculations, we have investigated the generality of a recently discovered mechanism that enhances the precipitation of the <span><math><msup is=\"true\"><mi is=\"true\">θ</mi><mo is=\"true\">′</mo></msup></math></span> precipitate phase through the dissolution of trace Au additions within <span><math><msup is=\"true\"><mi is=\"true\">θ</mi><mo is=\"true\">′</mo></msup></math></span>. We have designed a workflow to systematically screen chemical elements and found that, Pd and Pt can also enhance the precipitation of <span><math><msup is=\"true\"><mi is=\"true\">θ</mi><mo is=\"true\">′</mo></msup></math></span> by the same mechanism as Au. All these three elements are found to substitute Cu atoms within <span><math><msup is=\"true\"><mi is=\"true\">θ</mi><mo is=\"true\">′</mo></msup></math></span>, forming what we call “blended precipitates,” namely, precipitates containing regions of both <span><math><msup is=\"true\"><mi is=\"true\">θ</mi><mo is=\"true\">′</mo></msup></math></span> and another phase of nearly identical crystal structure (i.e., <span><math><mi is=\"true\">η</mi></math></span> (Al₂Au), Al₂Pt or Al₂Pd). According to our calculations, enhanced precipitation originates from the lowering of different energy contributions to the substitution of Cu atoms. Among these elements, Pt is the most promising choice for microalloying in the Al-Cu alloy system as it decreases both the formation energy of the <span><math><msup is=\"true\"><mi is=\"true\">θ</mi><mo is=\"true\">′</mo></msup></math></span> blended precipitate phase as well as the energy of its interface with the Al matrix. This work illustrates the effectiveness of the workflow developed here and should stimulate the exploration of other alloy systems displaying blended precipitate phases, with potentially improved mechanical properties.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"1 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142940113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First-principles prediction of diffusion coefficients in off-stoichiometric tantalum carbide","authors":"I. Khatri,&nbsp;R.K. Koju,&nbsp;Y. Mishin","doi":"10.1016/j.actamat.2025.120717","DOIUrl":"10.1016/j.actamat.2025.120717","url":null,"abstract":"<div><div>The tantalum carbide TaC is a promising ceramic material for ultra-high-temperature applications. Diffusion coefficients in this carbide are critically important for the synthesis optimization and under service conditions. Unfortunately, they remain largely unknown because their experimental measurements are highly challenging. This work aims to understand the atomistic mechanisms of Ta and C diffusion in TaC and evaluate the diffusion coefficients by combining first-principles calculations with a statistical–mechanical model of point defects and a diffusion kinetics theory. We focus on practically important carbon-deficient compositions and high temperatures ranging between 2000 K and 4000 K. The calculations show that carbon diffusion is extremely fast and mediated by single-vacancy jumps on the carbon sublattice. Ta diffusion is much slower and occurs predominantly by atomic exchanges with divacancies with a smaller contribution of trivacancies. Deviations from the perfect stoichiometry accelerate carbon diffusion but have little effect on the rate of Ta diffusion.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120717"},"PeriodicalIF":8.3,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142940161","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}