Acta Materialia最新文献

{"title":"Comparative analysis of piezoelectric regular foams from two types of Gibson–Ashby cells with uniform and piecewise homogeneous polarizations","authors":"Alexandr Kornievsky ,&nbsp;Andrey Nasedkin ,&nbsp;Aleksey Volkov","doi":"10.1016/j.actamat.2025.120744","DOIUrl":"10.1016/j.actamat.2025.120744","url":null,"abstract":"<div><div>Modern achievements in the development of additive technologies allow the creation of highly porous piezoelectric metamaterials with a specified microstructure. Preliminary computer simulation of their properties depending on the initial geometric and physical data opens up wide possibilities in the design of effective piezoelectric devices with unique characteristics. Gibson–Ashby cells are classic versions of elementary structures of metamaterials and their mechanical properties are well studied. However, piezoelectric metamaterials have been investigated to a much lesser extent. Thus, for cells made of piezoceramics, it is fundamentally important to know the type of inhomogeneous polarization field. We investigated two types of canonical Gibson–Ashby cells: symmetric one with four connecting edges on each face and asymmetric one with two connecting edges on each face. Regular lattices can be composed of these cells, which were also studied. In addition, we compared the structures with uniform and with piecewise uniform polarization of piezoceramics. Effective moduli were found from numerical solutions of homogenization problems using the finite element method. The results obtained allowed us to identify the anisotropy classes of a homogeneous material for all considered variants and to establish the influence of geometry and polarization field on effective moduli. New unusual properties of effective transverse piezoelectric moduli, different from the properties of the corresponding piezoelectric moduli of conventional piezoceramics, were noted.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120744"},"PeriodicalIF":8.3,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142989950","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":"Data science of the in silico crystallization","authors":"Alexey V. Redkov","doi":"10.1016/j.actamat.2025.120762","DOIUrl":"10.1016/j.actamat.2025.120762","url":null,"abstract":"<div><div>A data-driven approach is used to describe the growth of crystals and thin films based on high-throughput numerical experiments. This way the Machine Learning (ML) helps to reveal hidden patterns in the results from our atomistic-scale model which combines Cellular Automaton and Monte-Carlo moduli shaped as a Kossel crystal, through a carefully devised monitoring scheme, i.e. our computational <em>nanoscope</em>. Thus, from the quantities monitored in real-time, like growth rate and surface roughness, evolves the powerful concept of a <em>crystal growth kernel</em> — an ML-based comprehensive digital library that describes the growth of a crystal adequately across all the chosen ranges of system parameters, sizes, from atomistic to macroscopic, and growth modes — step-flow growth and instabilities, nucleation, rough growth, etc. Here we start with the analysis of how the kernel's prediction accuracy and time depend on the number of parameters.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"287 ","pages":"Article 120762"},"PeriodicalIF":8.3,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143128884","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":"Origin of superior energy storage performance in antiferroelectric relaxors","authors":"Pingji Ge,&nbsp;Ben Tian,&nbsp;Zhengkai Hong,&nbsp;Mengyao Liu,&nbsp;Sen Yang,&nbsp;Xiaoqin Ke","doi":"10.1016/j.actamat.2025.120759","DOIUrl":"10.1016/j.actamat.2025.120759","url":null,"abstract":"<div><div>Antiferroelectric relaxors (AFR) have attracted increasing attention for their potential to achieve large energy storage density and high efficiency simultaneously. However, the underlying mechanism behind their superior energy storage performance remains unclear. In this study, we establish a phase-field model of a doped antiferroelectric (AFE) systems by taking into account of the nanoscale compositional heterogeneity induced by random distribution of point defects as well as the associated local electric fields and local phase transition temperature variation. It is found that as the normal AFE transforms to AFR with defect concentration increasing, both the energy storage density and efficiency of the material increases, which is consistent with experimental results. The large energy storage density and high efficiency of AFR is ascribed to the “late” polarization saturation upon increasing external electric field and “early” depolarization initiation upon decreasing electric field due to the existence of larger local electric fields in directions nearly opposite to external fields in AFR materials, which leads to more elongated polarization-applied electric field loops. It is further found that although ferroelectric relaxors (FR) also have large local electric fields, the energy storage density is larger in AFR materials as compared to FR materials because the additional force to restore antiparallel polarization alignments inherent in AFR materials make the polarization saturation later and depolarization initiation earlier in AFR, leading to more elongated polarization-applied electric field loops. This study unravels the origin of high energy storage density of AFR and could provide theoretical guide to design high-performance energy storage materials.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120759"},"PeriodicalIF":8.3,"publicationDate":"2025-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988548","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":"Unlocking ultrahigh strength in dilute Al alloys: The synergy of stable grain boundary networks and solute clusters","authors":"L. Fang ,&nbsp;H.T. Xue ,&nbsp;B. Zhang ,&nbsp;Y. Kong ,&nbsp;Y.C. Xin ,&nbsp;W. Xu ,&nbsp;X.Y. Li","doi":"10.1016/j.actamat.2025.120758","DOIUrl":"10.1016/j.actamat.2025.120758","url":null,"abstract":"<div><div>The strength of Al alloys can be significantly enhanced through grain refinement and aging hardening. However, improving strength through aging hardening in nanograins is challenging due to the poor structural stability, which leads to grain growth and precipitation coarsening. Herein, a nanostructured AA6061 alloy with grain size of 26 nm and a high proportion of relaxed grain boundaries (GB) was fabricated using cryogenic high-pressure torsion (HPT). During aging treatment, Mg-Si-Cu co-segregated at GBs and high density of Mg-Si solute clusters (approximately 5.6 × 10²³ m^-3) rather than intermetallic precipitates formed within the nanograins, resulting in a record strength as high as 805 MPa. The solute clusters exhibited an excellent thermal stability against prolonged aging at higher temperatures, which can be attributed to the stable GB networks. This work presents a promising prototype for designing high strength and thermally stable nanocrystalline Al alloys through the synergy of stable GB networks and solute clusters.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120758"},"PeriodicalIF":8.3,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988557","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":"Hydrogen induced superhydrophilicity in an amorphous CrFeNi-based multi-principal element alloy thin film","authors":"Athanasios A. Papaderakis ,&nbsp;Eirini-Maria Paschalidou ,&nbsp;León Zendejas Medina ,&nbsp;Ezgi Hatipoglu ,&nbsp;Aparna Saksena ,&nbsp;Baptiste Gault ,&nbsp;Birhan Sefer ,&nbsp;David Malmström ,&nbsp;Pouya Hosseini ,&nbsp;Oliver Trost ,&nbsp;Adrianna Lozinko ,&nbsp;Mohini Ramkaran ,&nbsp;Anne Juel ,&nbsp;Kristina Tschulik ,&nbsp;Robert A.W. Dryfe","doi":"10.1016/j.actamat.2025.120756","DOIUrl":"10.1016/j.actamat.2025.120756","url":null,"abstract":"<div><div>The compelling nature of the highly adapted functional surface structures found in biological systems accompanied by delicately tuned chemical processes, has inspired the design of materials with varied wetting properties and a vast range of applications. Identifying relations between surface structure, chemistry and wettability, is pivotal towards the mechanistic understanding of wetting phenomena. Here we demonstrate how electrochemically driven hydrogen adsorption/absorption induces, irreversibly, a superhydrophilic state in an amorphous CrFeNi-based multi-principal element alloy thin film with close to equimolar composition, i.e., in the class of medium/high entropy alloys. By employing films with sub-nanometer roughness to exclude the influence of geometry on wetting, we show that both the extent of wetting and its dynamics are governed by the rate of the underlying electrochemical reactions. The absorption of hydrogen into the matrix of the amorphous films as proved by thermal desorption spectroscopy, is proposed to partially protonate the electrochemically resilient Ta and Cr surface oxides through a hydrogen spillover phenomenon initiated by the adsorption of hydrogen on the electrochemically reduced Fe sites. Furthermore, atom probe tomography measurements reveal Cr segregation at the outermost surface layers of the film following cathodic treatment. The above processes strongly influence surface energetics resulting in the transition from a mildly hydrophilic state to an ultra-high substrate surface energy regime. Our work establishes a previously unknown physicochemical link between multi-principal element-alloys – hydrogen interactions and surface wettability, that is of significance in frontline research areas spanning electrochemical energy conversion/storage and catalysis to materials degradation and liquids actuation.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120756"},"PeriodicalIF":8.3,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988683","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":"Complex deformation behavior of a partially recrystallized metastable medium-entropy alloy: In-situ synchrotron X-ray diffraction study","authors":"Jae Heung Lee ,&nbsp;Hyeonseok Kwon ,&nbsp;Gang Hee Gu ,&nbsp;Ji Yeong Lee ,&nbsp;Sang Guk Jeong ,&nbsp;Emad Maawad ,&nbsp;Changwan Ha ,&nbsp;Jae Bok Seol ,&nbsp;Sun Ig Hong ,&nbsp;Sangbong Yi ,&nbsp;Hyoung Seop Kim","doi":"10.1016/j.actamat.2025.120757","DOIUrl":"10.1016/j.actamat.2025.120757","url":null,"abstract":"<div><div>Ferrous medium-entropy alloys (FeMEAs), leveraging deformation-induced martensitic transformation (DIMT), demonstrate excellent strain-hardening ability attributed to the transformation-induced plasticity (TRIP) effect. To improve the low yield strength of FeMEAs, the initial microstructure was controlled by utilizing partial recrystallization. The intricate initial microstructure, a blend of recrystallized (ReX) and non-recrystallized (non-ReX) regions, results in complex deformation behavior where DIMT in both the ReX and non-ReX regions are simultaneously activated, posing significant analytical challenges. In this paper, we perform in-situ synchrotron X-ray diffraction during the tensile loading on a partially recrystallized metastable Fe_57.5Co₁₈Cr₁₃Ni_7.5Mo₃C₁ (at%) FeMEA to quantitatively analyze each deformation mechanism. The innovative idea of peak deconvolution enables separate tracing of the deformation behavior of the ReX and non-ReX FCC domains, revealing the stress partitioning between them. DIMT kinetics in each domain are investigated by the evolution of domain fractions, and we provide a detailed discussion on how both of them exhibit rapid DIMT kinetics. Furthermore, we measure the contributions of DIMT occurring in each domain on the global strain-hardening rate. The results suggest that the predominant contribution shifts from DIMT in the ReX domain to DIMT in the non-ReX domain as deformation progresses, highlighting the distinctive strain-hardening mechanisms between the ReX and non-ReX domains. This work demonstrates how a partially recrystallized metastable FeMEA exhibits superior mechanical properties and provides insights into analyzing the complex deformation behavior.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120757"},"PeriodicalIF":8.3,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988412","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":"Deformation faulting in ultrafine-grained aluminum alloys: Nucleation mechanisms and critical assessment of strengthening-ductilization contributions","authors":"Jingfan Zhang ,&nbsp;Xiuzhen Zhang ,&nbsp;Shaolou Wei ,&nbsp;Xinren Chen ,&nbsp;Shuaihang Pan ,&nbsp;Chao Yang ,&nbsp;Hucheng Pan ,&nbsp;Dengshan Zhou ,&nbsp;Deliang Zhang ,&nbsp;Gaowu Qin","doi":"10.1016/j.actamat.2025.120750","DOIUrl":"10.1016/j.actamat.2025.120750","url":null,"abstract":"<div><div>Stacking faults (SFs) have received a growing attention in recent years, and are currently incorporated in microstructure design to achieve a synergistic enhancement of strength and ductility for critical applications. However, unlike extensively studied nanotwins, the full potential of SFs in face-centered-cubic (fcc) metallic alloys, particularly in high stacking fault energy fcc Al-based materials, has remained less-explored and unutilized. In the present work, we engineered SFs-containing high-strength ultrafine-grained Al-Mg based alloys by extrusion deformation of mechanically alloyed powder compacts. These SFs tend to emit from grain boundaries (GBs) and matrix/precipitate interfaces during the extrusion deformation, exhibiting a heterogeneous spatial distribution in the resultant microstructures. Through theoretical analysis of the strengthening effects associated with diverse structural elements and detailed microscopic observations of SFs in the macroscopically yielded specimens, we find that GB- and hetero-interface-emitted SFs are incapable of providing substantial strengthening, but can effectively improve the plasticity of the materials. This finding is fundamentally inconsistent with the reported Al-based materials with SFs in which SFs are proposed to simultaneously enhance materials’ strength and plasticity. Hence, our results advance the current understanding of the role of SFs in modulating ductility of high-strength Al-based alloys by interface-emitted SFs.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120750"},"PeriodicalIF":8.3,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988027","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":"Stress-induced orthorhombic O phase in TiAl alloys","authors":"Xu Liu ,&nbsp;Lin Song ,&nbsp;Florian Pyczak ,&nbsp;Andreas Stark ,&nbsp;Li Wang ,&nbsp;Xiang Guo ,&nbsp;Tiebang Zhang","doi":"10.1016/j.actamat.2025.120751","DOIUrl":"10.1016/j.actamat.2025.120751","url":null,"abstract":"<div><div>The orthorhombic O phase precipitation within the D0₁₉-α₂ phase has attracted increasing attention recently in high Nb containing TiAl (high Nb-TiAl) alloys since the precipitation temperature is close to the expected service temperature of the alloys. In this study, in-situ synchrotron high energy X-ray diffraction (HEXRD) reveals that the O phase precipitates at 550 °C while it dissolves into the α₂ phase at 750 °C during heat treatments. However, under external stress the O phase unexpectedly precipitates from α₂ phase at 800 °C and even 900 °C. The O phase formation proceeds further in the presence of a critical stress promoted by internal stress accumulation in the α₂ phase, whereas the reverse O→α₂ phase transformation takes place when the internal stresses are relaxed. Additionally, it has been revealed that the O phase preferentially precipitates from specifically oriented α₂ grains with one of their &lt;11<span><math><mover><mn>2</mn><mo>¯</mo></mover></math></span>0&gt; directions aligned perpendicular and their 〈0001〉 directions rotated by an angle of 120° out of the external load axis. This α₂ phase orientation facilitates the α₂→O crystal transition during uniaxial compression. Transmission electron microscopy (TEM) study shows that stress-induced α₂→O transformation is governed by small atomic shifts in the α₂ lattice. In addition, the selective growth of certain O variants via shuffling along an [11<span><math><mover><mn>2</mn><mo>¯</mo></mover></math></span>0]_α2 direction is found to accommodate the external strain component in this direction.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120751"},"PeriodicalIF":8.3,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988028","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":"Nucleation behavior of the primary FCC-Al phase in a Al86Ni10MM4 metallic glass","authors":"Wan Kim ,&nbsp;Tianrui Duan ,&nbsp;Eun Soo Park ,&nbsp;John H. Perepezko","doi":"10.1016/j.actamat.2025.120754","DOIUrl":"10.1016/j.actamat.2025.120754","url":null,"abstract":"<div><div>The kinetics analysis of the heterogeneous nucleation behavior of primary FCC-Al in Al-based metallic glasses (MG) has been limited to a narrow temperature range below glass transition temperature due to the limited thermal test range available for conventional DSC (differential scanning calorimetry). Investigation of nucleation kinetics over wide temperature ranges has been a persistent challenge to clarify the kinetic competition between glass formation and nucleation of primary FCC-Al. To overcome this limitation, the Time-Temperature-Transition (TTT) diagram of primary FCC-Al in Al₈₆Ni₁₀MM₄ (MM: mischmetal) MG has been determined by thermodynamic calculations and nucleation delay time data measured at the high (near melting temperature) and low (near glass transition temperature) temperature region by Flash DSC (FDSC). By analyzing the break point of the increasing glass transition and crystallization temperatures resulting from annealing, the nucleation delay time of FCC-Al in the temperature range of 493 K to 513 K was determined. Quenching a molten Al₈₆Ni₁₀MM₄ MG at cooling rates over 33,000 K/s suppressed the formation of intermetallic phases, enabling the determination of the delay time of FCC-Al nucleation in the range of 750 K to 760 K from FDSC cooling curves by the additivity rule. Experimental delay time data, coupled with a statistical analysis on nucleation events during repeat runs observed at the cooling rate of 40,000K/s, provided valuable constraints on the assignment of kinetics parameters for the TTT diagram.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120754"},"PeriodicalIF":8.3,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988055","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":"Hydrogen decelerates fatigue induced grain boundary migration in nanostructured iron","authors":"M.W. Kapp, M. Zawodzki, M. Antoni, D. Zwittnig, M. Tkadletz, M. Moshtaghi, G. Mori, J. Eckert, O. Renk","doi":"10.1016/j.actamat.2025.120749","DOIUrl":"https://doi.org/10.1016/j.actamat.2025.120749","url":null,"abstract":"The difficulty to reveal trapping sites of hydrogen in metals, how hydrogen interacts with lattice defects and potentially changes their behavior, still prevents a generalized understanding of hydrogen (H)-embrittlement. This is specifically the case for nanostructured materials, where direct characterization techniques would require an exceptional lateral and time resolution, given the small grain size and high diffusivity of H. The tendency of nanostructures for grain coarsening under mechanical or thermal loads, adds further complexity to this issue. Cyclic high pressure torsion uses this peculiarity and allows to conclude whether H is located at grain boundaries or changes the deformation behavior. If hydrogen is trapped at grain boundaries, the kinetics of fatigue induced grain coarsening should clearly differ compared to the uncharged reference samples, while a change of the deformation behavior would manifest in a different texture evolution compared to the reference. The experiments clearly reveal that H prevents grain growth up to accumulated strains of <em>ε_acc</em> = 100, while it still decelerates boundary migration at even larger accumulated strains of <em>ε_acc</em> = 500. The results give thereby indirect proof of preferential H-defect-interaction. The occurrence of grain boundary deceleration rather than its acceleration strongly suggests that grain boundary pinning dominates over an amplifying effect on dislocation and disconnection mobility. Thus, the results indicate the importance of H-grain boundary interaction but also question the role of the hydrogen enhanced localized plasticity (HELP) theory in nanostructured iron.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"53 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142986593","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}