Acta Materialia最新文献

{"title":"Spectral model for grain boundary segregation in systems with strong solute–solute interactions","authors":"Georgiy Marchiy,&nbsp;Dmitry Samsonov,&nbsp;Eugene Mukhin","doi":"10.1016/j.actamat.2025.121044","DOIUrl":"10.1016/j.actamat.2025.121044","url":null,"abstract":"<div><div>Solute segregation at grain boundaries is emerging as a promising tool for the stabilization of polycrystals against grain growth. Modern approaches to segregation modeling are based on employing atomistic grain boundary segregation spectra. Currently, there is no spectral model that accounts for solute–solute interactions beyond the random mixing approximation. The paper shows that such interactions are crucial for the Ag(Ni) system, which is the focus of this study. We derive the Gibbs free energy for a spectral model of grain boundary segregation that properly captures solute–solute interactions strong enough to violate the random mixing assumption. Strong attractive interactions have been shown to be independent of solute concentration and can be directly incorporated into the segregation spectrum. Moreover, at zero temperature, all types of solute–solute interactions can be incorporated into the segregation spectrum, allowing the calculation of zero-temperature stability scores with regard to solute–solute interactions. This may enhance the reliability of screening for stable nanocrystalline alloys. Finally, the model incorporating solute–solute interactions into the segregation spectrum has been shown to provide a reliable approximation for systems exhibiting strong solute–solute interactions, even at moderate temperatures.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"294 ","pages":"Article 121044"},"PeriodicalIF":8.3,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143945852","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":"Mechanical properties of compositionally modulated epitaxial VN(001)/VC(001) films","authors":"Moishe Y.E. Azoff-Slifstein ,&nbsp;Anshuman Thakral ,&nbsp;Sadiq S. Nishat ,&nbsp;Md. Rafiqul Islam ,&nbsp;Patrick E. Hopkins ,&nbsp;Daniel Gall","doi":"10.1016/j.actamat.2025.121135","DOIUrl":"10.1016/j.actamat.2025.121135","url":null,"abstract":"<div><div>Epitaxial 1.5-μm-thick VN(001) and VC(001) films are deposited on MgO(001) by reactive magnetron sputtering in Ar/N₂ and Ar/CH₄ gas mixtures at <em>T_s</em> = 1000 °C, respectively. Cyclic switching between the Ar/N₂ and Ar/CH₄ gas yields compositionally modulated vanadium nitride/carbide films which exhibit a single-crystal epitaxial rock-salt structure matrix but also contain misoriented grains resulting in strongly facetted triangular 375–500 nm wide surface protrusions. The gas switching is adjusted to obtain films containing nominally identical amounts of VN and VC and various modulation periods Λ = 1.9 - 30 nm. They exhibit a stoichiometric anion-to-cation ratio but contain more carbon than nitrogen, suggesting that surface carbon reduces the N₂ sticking coefficient and the nitrogen incorporation rate. X-ray diffraction <em>θ</em>-2<em>θ</em> scans and reciprocal space maps indicate an in-plane compressive strain that decreases from -0.4 % to -0.1 % with increasing Λ, and a slightly decreasing relaxed lattice constant <em>a</em>_o = 4.160 - 4.155 Å. Hardness and elastic moduli measured by nanoindentation are <em>H</em>_VN = 5.1 GPa and <em>E</em>_VN = 226 GPa for VN(001), and <em>H</em>_VC = 19.4 GPa and <em>E</em>_VC = 323 GPa for VC(001). The hardness decreases from <em>H</em> = 16.4 – 11.1 GPa with increasing Λ = 1.9 - 30 nm, while the measured <em>E</em> = 260 ± 20 GPa is independent of Λ. Both <em>H</em> and <em>E</em> values are close to the theoretical isostress rule of mixtures (ROM) prediction, revealing that the modulated VN/VC films exhibit no hardness enhancement. This suggests that neither nitrogen-carbon intermixing nor composition modulation results in dislocation pinning during mechanical deformation. This is attributed to the relatively small 0.8 % VN/VC lattice mismatch which results in negligible local strain variations or coherency strains.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"294 ","pages":"Article 121135"},"PeriodicalIF":8.3,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143940141","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":"Practicing pseudo-binary diffusion couple method in ternary and multicomponent systems","authors":"Suman Sadhu ,&nbsp;Anuj Dash ,&nbsp;Neelamegan Esakkiraja ,&nbsp;Ujjval Bansal ,&nbsp;Avik Mondal ,&nbsp;Anindita Chakraborty ,&nbsp;Monojit Dutta ,&nbsp;Raju Ravi ,&nbsp;Surendra Makineni ,&nbsp;Saswata Bhattacharyya ,&nbsp;Sergiy Divinski ,&nbsp;Aloke Paul","doi":"10.1016/j.actamat.2025.121127","DOIUrl":"10.1016/j.actamat.2025.121127","url":null,"abstract":"<div><div>Solving the unresolved problem, the pseudo-binary (or quasi-binary or iso-concentration) diffusion couple method has emerged as an elegant and most frequently used research tool for diffusion analysis in multicomponent systems. This is practiced even in a ternary system for the systematic generation of composition-dependent diffusion coefficients, which is otherwise impossible following conventional methods. However, the analysis for the deviations from an “ideal pseudo-binary diffusion profile” is not standardized yet, leading to confusion in the acceptability of the estimated diffusion coefficients. This study explains the logic behind establishing an augmented Darken and Darken-Manning equation schemes suitable for pseudo-binary diffusion profiles considering experimentally produced diffusion profiles and extracted activity profiles of elements. The correct estimation method is demonstrated by producing pseudo-binary profiles up to a six-element system for the first time, depending on the ideal or non-ideal nature of the diffusion profiles. A re-adjustment factor (RAF) concept is introduced, reflecting on the effect of the non-ideality range on estimated diffusion coefficients. This is demonstrated based on several diffusion couple experiments in multiple systems of technological importance that produce different ranges of ideal, near-ideal, minor, and major non-ideal pseudo-binary diffusion profiles. RAF values provide an ultimate guideline for pseudo-binary diffusion analysis in multicomponent systems depending on the extent of non-ideality and composition range of the main diffusing elements. Additionally, the importance of estimating the tracer and intrinsic diffusion coefficients instead of only interdiffusion coefficients (reported mostly) is substantiated by estimating all types of diffusion coefficients when relevant.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"294 ","pages":"Article 121127"},"PeriodicalIF":8.3,"publicationDate":"2025-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143933323","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":"Phonon anharmonicity and thermal expansion in two-dimensional graphene/MoS2 and graphene/WS2 heterostructures: DFT and Raman study","authors":"Konrad Wilczyński,&nbsp;Arkadiusz P. Gertych,&nbsp;Mariusz Zdrojek","doi":"10.1016/j.actamat.2025.121133","DOIUrl":"10.1016/j.actamat.2025.121133","url":null,"abstract":"<div><div>Anharmonicity is a crucial feature of solid-state systems, affecting phenomena such as thermal expansion and temperature-dependent heat conductivity. Here, phonon anharmonicity in monolayer MoS₂, WS₂, and their heterostructures with graphene is comprehensively investigated, using ab-initio calculations and Raman spectroscopy. The presented theoretical approach yields exceptionally accurate predictions of temperature-dependent phonon frequencies in these systems. It is demonstrated that the friction regime between monolayers strongly affects thermal expansion in heterostructures – resulting in a tenfold difference in-plane expansion coefficients. Furthermore, significant impact of four-phonon processes is unveiled, contributing to approximately 1/3 of temperature-dependent frequency slopes (d<em>ω</em>/d<em>T</em>) in MoS₂ and WS₂ monolayers, although this factor has been commonly ignored in state-of-the-art theoretical works. This effect changes noticeably if a graphene cap layer is present, which, combined with the evolved thermal expansion, can flatten the d<em>ω</em>/d<em>T</em> slopes by 20 %. Our work introduces a novel approach to calculating phonon anharmonicity in complex, multi-layered two-dimensional structures, which might also support determining their macroscopic thermal properties.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"294 ","pages":"Article 121133"},"PeriodicalIF":8.3,"publicationDate":"2025-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143933322","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":"Combined measurements of composition-dependent tracer-, impurity- and intrinsic diffusion coefficients and atomic correlation factors from a binary diffusion couple","authors":"Neelamegan Esakkiraja ,&nbsp;Jasper Berndt ,&nbsp;Stephan Klemme ,&nbsp;Gerhard Wilde ,&nbsp;Aloke Paul ,&nbsp;Sergiy V. Divinski","doi":"10.1016/j.actamat.2025.121088","DOIUrl":"10.1016/j.actamat.2025.121088","url":null,"abstract":"<div><div>A fundamental understanding of atomic diffusion is crucial for technological advances in the application of multi-component alloys. The augmented tracer-interdiffusion couple approach provides the composition-dependent tracer diffusion coefficients (mobilities) along the whole diffusion path. This study introduces a novel methodology for accessing the vacancy flux calculations in a diffusion couple, substantiating a rich variety of the diffusion parameters accessible by a single diffusion couple experiment aside of the interdiffusion coefficients. We demonstrate that the composition-dependent thermodynamic factors and Manning’s factors can be estimated using this approach. Furthermore, the composition-dependent correlation factors of the diffusing elements in a diffusion couple are estimated for the first time. A modified tracer-interdiffusion couple approach is applied to estimate the composition-dependent impurity diffusion coefficients by placing suitable radiotracers at the Matano plane. The Onsager coefficients are estimated for the whole concentration range under investigation. Under the vacancy flux in the Ni–Fe diffusion couple, Cr, Co, and Mn atoms are biased towards the Ni-rich side, though the vacancy flux-driven drift of the Mn atoms is most pronounced.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"293 ","pages":"Article 121088"},"PeriodicalIF":8.3,"publicationDate":"2025-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143931131","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":"Chemical trends favoring interstitial cluster formation in bcc high-entropy alloys from first-principles calculations","authors":"Pedro P.P.O. Borges,&nbsp;Robert O. Ritchie,&nbsp;Mark Asta","doi":"10.1016/j.actamat.2025.121091","DOIUrl":"10.1016/j.actamat.2025.121091","url":null,"abstract":"<div><div>Achieving high strength and ductility is a common goal in structural alloy design. Body-centered cubic high-entropy alloys (HEAs) commonly highlight the conflict between these properties, with stronger alloys being brittle and vice versa. Recent reports suggest interstitial solutes can be used to overcome this trade-off, in some cases providing both strength and ductility enhancements. This effect has been correlated with interstitial cluster formation, although the conditions favoring their formation remain incompletely understood. Using first-principles calculations of solution energies and diffusivities, we provide insights into thermodynamic and kinetic factors favoring interstitial solute clusters. Among C, N and O solutes, O interstitials display most desirable diffusion kinetics. Further, the results highlight the importance of local composition fluctuations in the HEAs to enable the formation of clusters of appreciable size. The results are explained in terms of bonding and distortion trends across solutes and HEA compositions to provide guidelines for alloy design.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"294 ","pages":"Article 121091"},"PeriodicalIF":8.3,"publicationDate":"2025-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143931302","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 desorption of hydrogen in damaged materials and its implication for defect characterization","authors":"Hui-Zhi Ma ,&nbsp;Yu-Hao Li ,&nbsp;Yu-Ze Niu ,&nbsp;Yi-Chun Hua ,&nbsp;Xiang-Shan Kong ,&nbsp;Long Cheng ,&nbsp;Hong-Bo Zhou ,&nbsp;Gang Lu ,&nbsp;Fei Gao ,&nbsp;Guang-Hong Lu","doi":"10.1016/j.actamat.2025.121130","DOIUrl":"10.1016/j.actamat.2025.121130","url":null,"abstract":"<div><div>Defects are ubiquitous in materials and their characterization is essential to materials development and deployment, but an immensely challenging task. Here, we advocate that thermal desorption spectroscopy (TDS) of hydrogen (H) can be used as a microscope to probe irradiation defect configurations in nuclear materials. Although TDS is widely used to measure the desorption of H in damaged materials during isochronal annealing, its utility to characterize defect configurations is rather limited. In this work, taking H retention and desorption in pre-damaged tungsten (W) as an example, we demonstrate the potential of TDS to probe vacancies in W by means of first-principles based multiscale modeling. We show that TDS of H, combined with multiscale modeling, can provide information on vacancy size, concentration and distribution in pre-damaged W, with simulated TDS results closely consenting to experimental observations. In addition, we clarify the key factors in affecting the peak temperature of TDS and reveal that the de-trapping attempt frequency of H from the vacancy cluster and vacancy clustering during annealing could have a profound effect on H desorption, which has been always neglected previously. The present study highlights the importance of TDS of H towards a quantitative assessment of vacancies in damaged materials.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"294 ","pages":"Article 121130"},"PeriodicalIF":8.3,"publicationDate":"2025-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143931130","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":"Mechanisms of spall failure in niobium subjected to high-throughput laser-driven micro-flyer impact","authors":"Nicolò M. della Ventura ,&nbsp;Arezoo Zare ,&nbsp;Jacob M. Diamond ,&nbsp;Julia T. Pürstl ,&nbsp;Florent Mignerot ,&nbsp;Amit Sharma ,&nbsp;Ravit Silverstein ,&nbsp;Mason Holmes ,&nbsp;James B. Spicer ,&nbsp;Todd C. Hufnagel ,&nbsp;Matthew R. Begley ,&nbsp;Alejandro Strachan ,&nbsp;K.T. Ramesh ,&nbsp;Daniel S. Gianola","doi":"10.1016/j.actamat.2025.121079","DOIUrl":"10.1016/j.actamat.2025.121079","url":null,"abstract":"<div><div>Designing bcc alloys for shock resistance requires a fundamental understanding of the microstructural evolution and failure mechanisms under dynamic loading. However, two significant challenges arise. Firstly, conventional plate impact experiments are time-consuming and costly, limiting the acquisition of sufficient data to investigate these mechanisms. Secondly, the mechanistic understanding of deformation and failure in pure bcc metals remains limited, hindering purposeful alloy design strategies. To address these challenges, we employ a high-throughput laser-driven micro-flyer technique to establish the relationship between the spall failure of pure bcc niobium and its evolving microstructure at tensile strain rates of <span><math><mo>∼</mo></math></span> <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>6</mn></mrow></msup></mrow></math></span> s⁻¹. By varying flyer thickness, peak shock stress ranging from 7.3 to 15.3 GPa were achieved. Post-mortem microstructural analysis of samples recovered at incipient and advanced spall failure states reveals that failure occurs in a ductile manner through mixed intergranular and intragranular fractures. For cavities nucleating within grains, dislocation emission from void surfaces is identified as the controlling void growth mechanism up to a void radius of <span><math><mo>∼</mo></math></span>260 nm, after which cracks emanate from void surfaces extending outward along {101} planes. Local misorientation variations are observed around the cracks, with dislocation cells observed away from crack edges and high-angle grain boundaries at crack edges, revealing continuous dynamic recrystallization in regions of highly accumulated plastic strain. Our spall strength and microstructural evolution results are discussed in the context of analytical models for dynamic cavitation-driven failure.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"293 ","pages":"Article 121079"},"PeriodicalIF":8.3,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143926619","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":"Giant transformation strain and rotation in Ni-Pt nanoparticles caused by atomic ordering","authors":"Mor Levi ,&nbsp;Anuj Bisht ,&nbsp;Corentin Chatelier ,&nbsp;Clément Atlan ,&nbsp;Joël Eymery ,&nbsp;Steven Leake ,&nbsp;Peter Boesecke ,&nbsp;Marie-Ingrid Richard ,&nbsp;Eugen Rabkin","doi":"10.1016/j.actamat.2025.121129","DOIUrl":"10.1016/j.actamat.2025.121129","url":null,"abstract":"<div><div>We fabricated single crystalline faceted nanoparticles of near-stoichiometric NiPt alloy employing the solid state dewetting of Ni-Pt bilayers deposited on a sapphire substrate. The particles were annealed within the stability range of the ordered L1₀ phase. We uncovered recurrent changes of the fraction of disordered (100)-oriented particles, characterized by intermittent disorder-order transformations coupled with particle reorientation. The nucleation and expansion of ordered domains within the disordered (111)-oriented particles resulted in an increase of internal stresses and concomitant nucleation of twinning dislocations. Subsequent out-of-plane rotation <em>via</em> twinning has resulted in intermittent nanoparticles disordering due to the slip geometry in the ordered L1₀ phase. Notably, the re-orienting particles exhibited a macroscopic linear transformation strain reaching a value of 23 %. The discovery of ordering-induced particle rotation and reorientation in our study introduces a novel approach for engineering the functional properties of supported metal nanoparticles.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"294 ","pages":"Article 121129"},"PeriodicalIF":8.3,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143927179","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":"Effects of crystal lattice integrity on molybdenum sputtering with a combined steady-state incident atom distribution theory and MD simulation","authors":"Hailong Huang ,&nbsp;Guoyu Zhang ,&nbsp;Jiuxin Ning ,&nbsp;Weirong Ni ,&nbsp;Lu Cai ,&nbsp;Xiaodong Wang","doi":"10.1016/j.actamat.2025.121128","DOIUrl":"10.1016/j.actamat.2025.121128","url":null,"abstract":"<div><div>Material surfaces subjected to low-energy ion incidence experience dynamic changes in their composition and density owing to implantation and compound formation. We propose a fundamental assumption (<em>Y</em>_in = 1) for long-term steady-state incidence. Subsequently, a novel theory is proposed to describe the distribution of incident atom proportions on a material surface as a function of depth under steady-state conditions. The theory is based on the lifetime prediction and extension of an accelerator grid in a high-power electric propulsion thruster system. As compared with experimental results, the simulated sputtering yield is lower for <em>θ</em> &lt; 25° and <em>θ</em> &gt; 70° and higher for 25° &lt; <em>θ</em> &lt; 70° These results and scanning electron microscopy observations demonstrate that the differences between the microscopic simulations and macroscopic experimental results of the sputtering yield are due to the ‘crater’ structure on the material surface, which alters the average incident angle. The proposed theory and algorithm can be utilized to develop steady-state sputtering models in the field of classical mechanics.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"294 ","pages":"Article 121128"},"PeriodicalIF":8.3,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143931132","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}