Acta Materialia最新文献

{"title":"Standard deviation in maximum restoring force controls the intrinsic strength of face-centered cubic multi-principal element alloys","authors":"Fei Shuang ,&nbsp;Luca Laurenti ,&nbsp;Poulumi Dey","doi":"10.1016/j.actamat.2024.120508","DOIUrl":"10.1016/j.actamat.2024.120508","url":null,"abstract":"<div><div>In this study, we explore the mechanisms underlying the exceptional intrinsic strength of face-centered cubic (FCC) Multi-Principal Element Alloys (MPEAs) using a multifaceted approach. Our methods integrate atomistic simulations, informed by both embedded-atom model and neural network potentials, with first-principles calculations, stochastic Peierls-Nabarro (PN) modeling, and symbolic machine learning. We identify a consistent, robust linear correlation between the strength of MPEAs and the standard deviation of the maximum stacking-fault restoring force (<em>τ</em>_max,sd) across various potentials. This finding is substantiated by comparing the experimental strengths of Cantor alloys’ subsystems and Ni_62.5V_37.5 against <em>τ</em>_max,sd values from high-throughput first-principle calculations. Our theoretical insights are derived from integrating the stochastic Peierls-Nabarro model with a shearable precipitation hardening framework, demonstrating that lattice distortion alone does not directly enhance intrinsic strength. Instead, <em>τ</em>_max,sd emerges as a critical determinant, capable of boosting the strength of MPEAs by up to tenfold. Our analysis reveals the critical role of the exponential form of the PN model in achieving substantial strength improvement by transforming the Gaussian-like distribution of <em>τ</em>_max into an exponential-like distribution of local Peierls stress. Additionally, using an advanced symbolic machine learning technique, the sure independence screening and sparsifying operator (SISSO) method, we derive interpretable relationships between MPEA strength, elastic properties, and <em>τ</em>_max statistics, offering new insights into the design and optimization of advanced MPEAs. These findings highlight that the nonlinear physics and atomic fluctuations characterizing MPEAs not only underpin their unconventional intrinsic strength but also contribute to other complex properties such as sluggish diffusion and cocktail effect.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"282 ","pages":"Article 120508"},"PeriodicalIF":8.3,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142566092","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":"Slip transfer and crack initiation at grain and twin boundaries during strain-controlled fatigue of solution-hardened Ni-based alloys","authors":"I. Escobar-Moreno,&nbsp;E. Nieto-Valeiras,&nbsp;J. LLorca","doi":"10.1016/j.actamat.2024.120497","DOIUrl":"10.1016/j.actamat.2024.120497","url":null,"abstract":"<div><div>Slip transfer/blocking at grain and twin boundaries as well as preferential fatigue crack nucleation locations were studied in two solution-hardened Ni-based alloys (Inconel 600 and Hastelloy C276) deformed under strain-controlled, fully-reversed cyclic deformation in the low-cycle fatigue regime. Electron backscatter diffraction-based slip trace analysis was used to identify the active slip systems after interrupted fatigue tests. It was found that the Luster-Morris parameter <span><math><mrow><msup><mrow><mi>m</mi></mrow><mrow><mo>′</mo></mrow></msup><mo>=</mo><mn>0</mn><mo>.</mo><mn>6</mn></mrow></math></span> was an accurate geometrical criteria to discriminate between slip transfer and blocking at grain and twin boundaries. Moreover, it was found that fatigue cracks initiation was always intergranular and cracks were nucleated at grain and twin boundaries when the slip transfer across was blocked. The probability of crack nucleation increased with the misorientation angle and was independent of the grain size. This behavior was associated with the development of stress concentrations at grain and twin boundaries as well as triple junctions in which slip was blocked and is different from previous reports on fatigue crack nucleation in Ni-based superalloys deformed, in which the slip system parallel to the TB in the parent grain was suitably oriented for slip. This contrast in the fatigue crack nucleation sites between both types of Ni alloys were attributed to the differences in the degree of strain localization and show how this factor controls damage nucleation in polycrystals.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"283 ","pages":"Article 120497"},"PeriodicalIF":8.3,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142566131","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":"Nb-doped coherent TiO2/LaAlO3 interfaces: Segregation mechanism and improved photocatalytic performance","authors":"Xiang Li ,&nbsp;Yixiao Jiang ,&nbsp;Qianqian Jin ,&nbsp;Fei Qin ,&nbsp;Tingting Yao ,&nbsp;Ang Tao ,&nbsp;Xuexi Yan ,&nbsp;Chunyang Gao ,&nbsp;Zhiqing Yang ,&nbsp;Chunlin Chen ,&nbsp;Gang Liu ,&nbsp;Xiu-Liang Ma ,&nbsp;Hengqiang Ye","doi":"10.1016/j.actamat.2024.120504","DOIUrl":"10.1016/j.actamat.2024.120504","url":null,"abstract":"<div><div>Elemental doping at coherent interfaces is very difficult and rarely used to improve the interfacial properties since coherent interfaces have low interfacial energies and lack open space for trapping dopant atoms. Exploring universally applicable strategies for elemental doping at coherent interfaces represents an important progress in interface science and engineering. In this study, Nb atoms are successfully doped at coherent (001) LaAlO₃/anatase-TiO₂ interfaces, which enhances greatly the efficiency of photocatalytic hydrogen production from water. Transmission electron microscopy investigations reveal that both LaO- terminated and AlO₂-terminated LaAlO₃/anatase-TiO₂ interfaces can trap two layers of Nb atoms, which accompanies with the formation of La vacancies between them. First-principles calculations suggest that Nb atoms segregate at the interfaces under the action of potential gradient, which increases significantly the strength of the built-in electric field in TiO₂, thereby facilitating the separation of photogenerated carriers and improving the photocatalytic performance. The H₂ production of the Nb doped coherent interface is about 4 times that of the pristine coherent interface. Since potential gradient widely exists at various interfaces including the coherent ones, elemental doping by potential gradient should be an universally applicable fabrication method for tuning the properties of interfaces and heterostructures.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"282 ","pages":"Article 120504"},"PeriodicalIF":8.3,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142556405","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":"A new approach to solid-state nucleation in kinetically-constrained systems","authors":"Christopher Hutchinson,&nbsp;Yves Brechet","doi":"10.1016/j.actamat.2024.120521","DOIUrl":"10.1016/j.actamat.2024.120521","url":null,"abstract":"<div><div>Nucleation is the first step of the phase transformations that we use to control the microstructures of engineering materials. The starting point for questions of nucleation is usually Classical Nucleation Theory (CNT) but for solid-state nucleation at low temperatures where atomic mobility is limited, such as in engineering alloys, CNT has not been very successful is quantitatively predicting nucleation. A strong assumption of CNT is that all thermally-induced stochastic fluctuations, no matter how far their compositions lie from the bulk alloy composition, are possible and that they become nuclei when a critical size determined from thermodynamics is reached.</div><div>Here we present a new and complementary model for solid-state nucleation. We consider the other extreme where atomic mobility is limited and thermally-induced stochastic clusters cannot form in the time scale relevant for a nucleation event. Instead, we consider the geometric clusters that are a statistical feature of any solution as the origin of the nuclei and present a simple model for the number of nuclei and their rate of ‘activation’. This new ‘geometric cluster’ model is shown to be able to successfully predict the competition in phase nucleation during the crystallization of a series of Al-Ni-Y metallic glass, predict the solvent trapping that is increasingly seen in solid-state nucleation and predict the peak number density of precipitates observed in Cu-Co and Fe-Cu alloys.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"283 ","pages":"Article 120521"},"PeriodicalIF":8.3,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142556409","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":"Enhanced reliability of Cu-Sn bonding through the microstructure evolution of nanotwinned copper","authors":"Xinyu Jin ,&nbsp;Huahan Li ,&nbsp;Yingying Sun ,&nbsp;Zhiqin Chen ,&nbsp;Peixin Chen ,&nbsp;Hongwei Su ,&nbsp;Ming Li ,&nbsp;Yunwen Wu","doi":"10.1016/j.actamat.2024.120524","DOIUrl":"10.1016/j.actamat.2024.120524","url":null,"abstract":"<div><div>Kirkendall voids are detrimental to the Cu-Sn bonding interface, causing the failure of the high-density package. Herein, the perpendicularly aligned nanotwinned Cu (p-ntCu) and the horizontally aligned nanotwinned Cu (h-ntCu) are prepared by controlling the electrodeposition procedure. The p-ntCu shows advantages both in fast-bonding process and in void suppression through the in-situ microstructure evolution. Compared with h-ntCu, the abundant perpendicularly aligned twin boundaries in p-ntCu provide fast interdiffusion paths to build a bonding interface. In the bonding process, p-ntCu grows to ultra-large-grained Cu with an average grain size of 6.68 μm. The reduced density of normal grain boundaries in p-ntCu lowers the Cu diffusion rate and contributes to more balanced interdiffusion at the bonding interface, which is confirmed by molecular dynamics simulation and kinetic calculations of intermetallic compound (IMC) growth. In addition, the low impurity content in p-ntCu further reduces the diffusion flux imbalance and limits the nucleation of Kirkendall vacancies. Consequently, the p-ntCu/Sn interface keeps void-free during 150 °C long-term thermal aging due to the synergistic effect of reduced grain-boundary diffusion and lower impurity content, which will be beneficial for achieving high-reliability Cu-Sn bonding.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"283 ","pages":"Article 120524"},"PeriodicalIF":8.3,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142542108","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":"Magnetic field controlled surface localization of ferromagnetic resonance modes in 3D nanostructures","authors":"Mateusz Gołębiewski ,&nbsp;Krzysztof Szulc ,&nbsp;Maciej Krawczyk","doi":"10.1016/j.actamat.2024.120499","DOIUrl":"10.1016/j.actamat.2024.120499","url":null,"abstract":"<div><div>By extending the current understanding and use of magnonics beyond conventional planar systems, we demonstrate the surface localization of ferromagnetic resonance (FMR) modes through the design of complex three-dimensional nanostructures. Using micromagnetic simulations, we systematically investigate woodpile-like scaffolds and gyroids — periodic chiral entities characterized by their triple junctions. The study highlights the critical role of demagnetizing fields and exchange energy in determining the FMR responses of 3D nanosystems, especially the strongly asymmetric distribution of the spin-wave mode over the system’s height. Importantly, the top–bottom dynamic switching of the surface mode localization across the structures in response to changes in magnetic field orientation provides a new method for controlling magnetization dynamics. The results demonstrate the critical role of the geometric features in dictating the dynamic magnetic behavior of three-dimensional nanostructures, paving the way for both experimental exploration and practical advances in 3D magnonics.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"283 ","pages":"Article 120499"},"PeriodicalIF":8.3,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142541450","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":"On identifying dynamic length scales in crystal plasticity","authors":"Dénes Berta ,&nbsp;David Kurunczi-Papp ,&nbsp;Lasse Laurson ,&nbsp;Péter Dusán Ispánovity","doi":"10.1016/j.actamat.2024.120506","DOIUrl":"10.1016/j.actamat.2024.120506","url":null,"abstract":"<div><div>Materials are often heterogeneous at various length scales, with variations in grain structure, defects, and composition which has a strong influence on the emergent macroscopic plastic behavior. In particular, heterogeneities lead to fluctuations in the plastic response in the form of jerky flow and ubiquitous strain bursts. One of the crucial aspects of plasticity modeling is scale bridging: In order to deliver physically correct crystal plasticity models, one needs to determine relevant microstructural length scales. In this paper we advance the idea that continuum descriptions of dislocation mediated plasticity cannot neglect dynamic correlations related to the avalanche behavior. We present an extensive weakest link analysis of crystal plasticity by means of three-dimensional discrete dislocation dynamics simulations with and without spherical precipitates. We investigate strain bursts and related length scales and conclude that while sufficiently strong obstacles to dislocation motion tend to confine the dislocation avalanches within well-defined sub-volumes, in pure dislocation systems the avalanches may span the system, implying that the dynamic length scale is, in fact, the size of the entire sample. Consequences of this finding on continuum modeling are thoroughly discussed.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"283 ","pages":"Article 120506"},"PeriodicalIF":8.3,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142541510","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":"Step flow mechanism in dissolutive wetting Cu/Ni systems","authors":"Youqing Sun ,&nbsp;Zhongfu Cheng ,&nbsp;K. Vijay Reddy ,&nbsp;Diqiu He ,&nbsp;Ensieh Yousefi ,&nbsp;Miral Verma ,&nbsp;Nele Moelans ,&nbsp;Muxing Guo ,&nbsp;David Seveno","doi":"10.1016/j.actamat.2024.120519","DOIUrl":"10.1016/j.actamat.2024.120519","url":null,"abstract":"<div><div>The Cu-Ni system is a typical dissolutive system due to its mutual dissolution across a wide range of temperatures and compositions. We characterized the effects of Ni dissolution on the wetting behavior of liquid Cu by combining high-temperature wetting experiments, in-situ observation of spreading and solidification, microstructure analysis of the quenched droplets, and computational fluid dynamic (CFD) simulations. In the very early moment, at 1100 °C, when the Cu droplet is brought in contact with the Ni substrate, it oscillates due to capillarity and is dampened by inertial effects, while the significant Ni dissolution at 1150 °C largely reduced the initial oscillations. Later, a peculiar spreading behavior is observed and we propose to describe it through a 4-step mechanism: pinning of the contact line by a newly formed solid solution layer at the interface acting as a physical barrier, driving of liquid towards the solidified edge due to a Ni-concentration induced Marangoni flow, forming of a precursor film ahead of the solidified edge caused by the strong Cu-Ni interactions and Marangoni flow, and finally depinning due to overflow as a result of liquid accumulation at the solidified edge. The formation of a solid solution layer is confirmed by in-situ observation and quenching. The Ni-concentration induced Marangoni flow is characterized experimentally and further investigated by CFD simulations. The proposed step flow mechanism can be potentially relevant to other dissolutive wetting systems (e.g. Bi/Sn, Ag/Cu and Cu/Fe systems), which are crucial for high-temperature processing techniques.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"282 ","pages":"Article 120519"},"PeriodicalIF":8.3,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519701","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":"Shrinkage and deformation of material extrusion 3D printed parts during sintering: Numerical simulation and experimental validation","authors":"Sri Bharani Ghantasala ,&nbsp;Gurminder Singh ,&nbsp;Jean-Michel Missiaen ,&nbsp;Didier Bouvard","doi":"10.1016/j.actamat.2024.120518","DOIUrl":"10.1016/j.actamat.2024.120518","url":null,"abstract":"<div><div>Material extrusion 3D printing (ME3DP) combined with sintering is a low-cost additive manufacturing technique for fabricating components of difficult-to-print metals, such as copper, aluminum, and ceramics. However, the sintering process includes complex material science, such as volumetric shrinkage and free structural bending, to identify the relative density and deformation of a 3D printed sample. The prediction of the relative density and deformations during the sintering process provides information to the design engineer to optimize the design of the CAD model before sintering. In this study, a phenomenological model based on constitutive equations was developed to predict the density and structural deformation during the sintering process of pure copper components fabricated by ME3DP using metal injection molding feedstock. The densification rate was determined using shrinkage estimation with an isothermal stairway heating cycle in a vertical dilatometer. Furthermore, different sets of experiments were performed with a load on the probe with long isothermal heating cycles at 850, 900, 950, 1000, and 1050 °C in a vertical dilatometer to estimate the axial viscosity of the copper. The constitutive equations were solved using the solid mechanics module with user-defined creep in COMSOL Multiphysics by considering isotropic assumptions. Two types of geometries, cube and overhanging I section, were used to predict shrinkage and deformation during the sintering process. The developed model successfully predicted the relative density based on shrinkage and structural deformation owing to gravity during the sintering process.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"282 ","pages":"Article 120518"},"PeriodicalIF":8.3,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519668","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":"Magnetic imaging of thermally switchable antiferromagnetic/ferromagnetic modulated thin films","authors":"W. Griggs ,&nbsp;A. Peasey ,&nbsp;F. Schedin ,&nbsp;Md.S. Anwar ,&nbsp;B. Eggert ,&nbsp;M.-A. Mawass ,&nbsp;F. Kronast ,&nbsp;H. Wende ,&nbsp;R. Bali ,&nbsp;T. Thomson","doi":"10.1016/j.actamat.2024.120515","DOIUrl":"10.1016/j.actamat.2024.120515","url":null,"abstract":"<div><div>Nanoscale magnetic patterning can lead to the formation of a variety of spin textures, depending on the intrinsic properties of the material and the microstructure. Here we report on the spin textures formed in laterally patterned antiferromagnetic (AF)/ferromagnetic (FM) thin film stripes with a period of 200 nm (100 nm FM/100 nm AF). We make use of the AF to FM phase transition in FeRh thin films at ∼100 °C, thereby creating a nanoscale pattern that is thermally switchable between AF/FM stripes and uniformly FM. A combination of spin-resolved photoemission electron microscopy, magnetic force microscopy, and magnetometry measurements allow direct nanoscale observations of the stray magnetic fields emergent from the nanopattern as well as the underlying magnetisation. Our measurements reveal pinning centres resistant to temperature cycling that govern the modulated spin-texture as well as a sub-texture consisting of grain-driven nanoscale magnetisation structure directed out of the film plane. The nanoscale magnetic structure is thus strongly influenced by the film microstructure. Signatures of exchange bias are not observed, most likely due to the small contact area between the AF and FM regions, combined with the fact that the interfaces between the damaged and undamaged regions are likely to be highly diffuse owing to the lateral scattering of incoming ions. These results show that temperature controllable spin textures can be created in FeRh thin films which could find application in domain wall, microwave, or magnonic devices.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"283 ","pages":"Article 120515"},"PeriodicalIF":8.3,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142520115","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}