Acta Materialia最新文献

{"title":"Regular vs. Inverted structure in Heusler compounds, high-throughput DFT study of Burch rule in X2YZ (X, Y = Ti, V, Cr, Mn, Fe, Co, Ni, Cu; Z = Al, Ga, Si, Ge, Sn)","authors":"Jerzy Goraus","doi":"10.1016/j.actamat.2026.122015","DOIUrl":"10.1016/j.actamat.2026.122015","url":null,"abstract":"<div><div>Full Heusler compounds crystallize most often in the regular Cu₂MnAl-type structure, whereas the inverted structure of CuHg₂Ti-type is seldom encountered, mostly in Mn-based compounds. The inverted structure is much more interesting as it enables the Spin-Gapless-Semiconductor (SGS) or Half-Metallic Ferromagnet (HMF) state for many potential stoichiometries containing cheap and abundant elements such as Ti₂MnAl. A general heuristic rule (Burch rule), proposed decades ago, states that the inverse structure is formed when the atomic number of Y is larger than the atomic number of X in the same period for the general formula X₂YZ. Here, we performed a series of DFT calculations for <span><math><mrow><mn>3</mn><mi>d</mi></mrow></math></span> metals ranging from Ti to Cu, and for Z = Al, Ga, Si, Ge, Sn to check whether this rule applies. We found that the inverted structure exists in three (or less often two) regions of stability across the XY plane, with the biggest region contributing the most to the perceived Burch rule validity. However, on the boundaries of these regions, the Burch rule is not fulfilled (as in the case of Ti₂MnAl). We also provide approximate formula for lattice parameters of these compounds depending on the atomic number of constituent elements. Magnetic moments calculated for both structures are also presented, showing exceptions to the Slater–Pauling rule. A notable such exception is V₃Al which is a well known fully compensated ferrimagnet. We include a list of such compounds where we found similar situation in our paper.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"308 ","pages":"Article 122015"},"PeriodicalIF":9.3,"publicationDate":"2026-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146187152","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":"Controlling interface atomic structure and distribution of oxide particles for improved ductility in Mo alloys","authors":"Z. Dong,&nbsp;M. Wang,&nbsp;M.X. Huang","doi":"10.1016/j.actamat.2026.121961","DOIUrl":"10.1016/j.actamat.2026.121961","url":null,"abstract":"<div><div>Achieving a synergistic balance between strength and ductility remains a longstanding challenge for molybdenum (Mo) alloys. In this study, we systematically investigate three Mo alloys reinforced with different oxide particles (Y₂O₃, CeO₂, and (Ce,Y)_xO_y), all exhibiting comparable yield strengths. The Mo-Y₂O₃ alloy contains disordered, incoherent Y₂O₃/Mo interfaces that generate severe local stress concentrations and premature interface decohesion, resulting in negligible uniform elongation. In contrast, the Mo-CeO₂ alloy features semi-coherent CeO₂(200)//Mo(101) interfaces that enhance dislocation storage capacity and yield a uniform elongation of 6.3%. Remarkably, the co-addition of CeO₂ and Y₂O₃ produces novel (Ce,Y)_xO_y particles, with a y/x ratio of approximately 1.7, that exhibit a CeO₂<span><math><mrow><mo>(</mo><mn>11</mn><mover><mrow><mn>1</mn></mrow><mo>‾</mo></mover><mo>)</mo></mrow></math></span>//Mo(200) incoherent interface. This tailored interface permits dislocation glide with moderate resistance, enabling sustained dislocation accumulation without severely restricting mobility. Furthermore, the Mo-CeO₂-Y₂O₃ alloy exhibits an optimized oxide distribution, promoting a homogeneous and fully recrystallized microstructure, thereby mitigating intergranular fracture and further improving ductility. As a result, the Mo-CeO₂-Y₂O₃ alloy achieves uniform and total elongations of 11.8% and 33%, respectively, nearly double those of the Mo-CeO₂ alloy and far exceeding those of the Mo-Y₂O₃ alloy. Our research highlights the pivotal role of strategic oxide design in controlling interface atomic structure, oxide distribution, and grain microstructure in Mo alloys, offering a promising pathway to strong and ductile oxide dispersion-strengthened metals.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"307 ","pages":"Article 121961"},"PeriodicalIF":9.3,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146032909","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":"Direct observation of nanoscale pinning centers in Ce(Co0.8Cu0.2)5.4 permanent magnets","authors":"Nikita Polin ,&nbsp;Shangbin Shen ,&nbsp;Fernando Maccari ,&nbsp;Alex Aubert ,&nbsp;Esmaeil Adabifiroozjaei ,&nbsp;Tatiana Smoliarova ,&nbsp;Yangyiwei Yang ,&nbsp;Xinren Chen ,&nbsp;Yurii Skourski ,&nbsp;Alaukik Saxena ,&nbsp;András Kovács ,&nbsp;Rafal E. Dunin-Borkowski ,&nbsp;Michael Farle ,&nbsp;Bai-Xiang Xu ,&nbsp;Leopoldo Molina-Luna ,&nbsp;Oliver Gutfleisch ,&nbsp;Baptiste Gault ,&nbsp;Konstantin Skokov","doi":"10.1016/j.actamat.2026.121906","DOIUrl":"10.1016/j.actamat.2026.121906","url":null,"abstract":"<div><div>Permanent magnets containing rare earth elements are essential components for the electrification of society. Ce(Co_1-xCu_x)₅ permanent magnets are a model system known for their substantial coercivity, yet the underlying mechanism remains unclear. Here, we investigate Ce(Co_0.8Cu_0.2)_5.4 magnets with a coercivity of ∼1 T. Using transmission electron microscopy (TEM) and atom probe tomography (APT), we identify a nanoscale cellular structure formed by spinodal decomposition. Cu-poor cylindrical cells (∼5–10 nm in diameter, ∼20 nm long) have a disordered CeCo₅-type structure and a composition Ce(Co_0.9Cu_0.1)_5.3. Cu-rich cell boundaries are ∼ 5 nm thick and exhibit a modified CeCo₅ structure, with Cu ordered on the Co sites and a composition Ce(Co_0.7Cu_0.3)_5.0. Micromagnetic simulations demonstrate that the intrinsic Cu concentration gradients up to 12 at.% Cu/nm lead to a spatial variation in magnetocrystalline anisotropy and domain wall energy, resulting in effective pinning and high coercivity. Compared to Sm₂Co₁₇-type magnets, Ce(Co_0.8Cu_0.2)_5.4 displays a finer-scale variation of conventional pinning with lower structural and chemical contrast in its underlying nanostructure. The identification of nanoscale chemical segregation in nearly single-phase Ce(Co_0.8Cu_0.2)_5.4 magnets provides a microstructural basis for the long-standing phenomenon of \"giant intrinsic magnetic hardness\" in systems such as SmCo_5-xM_x, highlighting avenues for designing rare-earth-lean permanent magnets via controlled nanoscale segregation.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"307 ","pages":"Article 121906"},"PeriodicalIF":9.3,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145919764","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":"Discovery and characterization of a silicon aluminum scandate (SAS) material","authors":"Kevin Yu ,&nbsp;Jamesa Stokes ,&nbsp;Kunal K. Jha ,&nbsp;Bryan Harder ,&nbsp;Hosea M. Nelson ,&nbsp;Katherine T. Faber","doi":"10.1016/j.actamat.2026.121949","DOIUrl":"10.1016/j.actamat.2026.121949","url":null,"abstract":"<div><div>A newly discovered doped silicon aluminum scandate (SAS) phase was successfully isolated and synthesized. Microcrystal electron diffraction was employed to determine the doped SAS crystal structure, revealing a triclinic (<em>P</em><span><math><mover><mrow><mn>1</mn></mrow><mo>‾</mo></mover></math></span>) unit cell with the nominal formula Si₂Al₂Sc₁₄O₂₈ with minority dopants of CaO, MgO, Fe₂O₃, and TiO₂. Powder X-ray diffraction and Rietveld refinement confirmed the structure of the doped SAS material. Electron-probe microanalysis and solid-state nuclear magnetic resonance were used to better understand the composition and local structure of the doped SAS phase. The results indicated that there are extensive cation substitutions within the doped SAS material. Differential thermal analysis on doped SAS demonstrated that the material is thermally stable up to 2150 °C, suggesting potential for refractory applications. Additional characterization, enabled by the solved structure of doped SAS, focused on relevant properties for refractory materials. The thermal expansion behavior of the doped SAS material was evaluated using high-temperature, <em>in situ</em> X-ray diffraction, while the reaction pathway for SAS formation was determined using a combination of high-temperature X-ray diffraction and annealing experiments. Ultimately, this study defines the structure, composition, and thermal behavior of the doped SAS material, while also highlighting the utility of microcrystal electron diffraction for structure determination of complex oxide phases.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"307 ","pages":"Article 121949"},"PeriodicalIF":9.3,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146006384","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":"Strain-gradient-driven decoupling of thermal suppression from anisotropy in β-Ga2O3","authors":"Guangwu Zhang ,&nbsp;Xing Xiang ,&nbsp;Ziyan Qian ,&nbsp;Yixin Xu ,&nbsp;Shengying Yue ,&nbsp;Hyejin Jang ,&nbsp;Lin Yang ,&nbsp;Yanguang Zhou ,&nbsp;Xinyu Wang ,&nbsp;Qiye Zheng","doi":"10.1016/j.actamat.2026.121973","DOIUrl":"10.1016/j.actamat.2026.121973","url":null,"abstract":"&lt;div&gt;&lt;div&gt;β-Ga&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; is an emerging ultra‑wide‑bandgap semiconductor (UWBGS) for efficient, high‑frequency power electronics, solar‑blind/UV photodetectors, and wearable/flexible devices, with scalable manufacturing. However, its intrinsically low thermal conductivity (&lt;em&gt;k&lt;/em&gt;)—compounded by ubiquitous, nonuniform strains introduced during fabrication and operation—creates a stringent thermal‑management bottleneck that degrades heat dissipation, reliability, and performance. Consequently, understanding how uniform and non-uniform strains affect thermal transport in this UWBG material is essential for thermal management design. Yet, strain gradients (&lt;em&gt;η&lt;/em&gt;), pervasive in flexible devices and epitaxial nanostructures, remain a major blind spot in β-Ga&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; thermal transport studies. By integrating the first-principles-based machine learning interatomic potential with Boltzmann transport equation, we establish that &lt;em&gt;η&lt;/em&gt; unlocks a &lt;em&gt;k&lt;/em&gt; suppression mechanism fundamentally more potent than uniform strain (&lt;em&gt;ε&lt;/em&gt;): moderate uniaxial gradients (0.6 %/nm) suppress &lt;em&gt;k&lt;/em&gt; by 32–37 % (27–30 %) in thin films (nanowires), intensifying to 43.3 % with biaxial gradients. This reduction far exceeds that from equivalent &lt;em&gt;ε&lt;/em&gt; and surpasses benchmark materials like silicon and BAs. Notably, β-Ga&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; exhibits a unique magnitude-anisotropy decoupling under &lt;em&gt;η&lt;/em&gt;: whereas uniform &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;ε&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;(±3 %) modifies thermal anisotropy ratios by ∼25 %, &lt;em&gt;η&lt;/em&gt; strongly suppresses the absolute &lt;em&gt;k&lt;/em&gt; while leaving these ratios nearly unchanged. This pronounced suppression originates from gradient-induced symmetry breaking and enhanced mode coupling, which activate otherwise forbidden phonon-scattering channels and make gradient-driven scattering dominant below 6.25 THz. Unlike cubic crystals (e.g., Si) under bending—where a through-thickness strain gradient predominantly suppresses heat flow along the bending direction while leaving the orthogonal in-plane component comparatively intact, thereby tuning anisotropy—monoclinic β-Ga&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; exhibits stronger cross-direction coupling due to its non-orthogonal crystallographic framework, so the same gradient suppresses multiple &lt;em&gt;k&lt;/em&gt; components. Consequently, phonon lifetimes are reduced broadly across transport directions, while concurrent changes in phonon group velocities partially compensate, yielding an approximately invariant anisotropy ratio even as &lt;span&gt;&lt;math&gt;&lt;mi&gt;k&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; collapses. By contrast, κ-Ga&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; shows a weaker &lt;em&gt;k&lt;/em&gt; reduction and pronounced anisotropy suppression under &lt;span&gt;&lt;math&gt;&lt;mi&gt;η&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;, confirming that the decoupling is unique in β-Ga&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;. These findings redefine non-uniform strain from a parasitic flaw into a powerful design tool for engineering thermal isolation and heat flux ","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"307 ","pages":"Article 121973"},"PeriodicalIF":9.3,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146072289","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":"Reconciling ultrahigh strength and hydrogen embrittlement resistance via discontinuous L12 precipitation in a high-entropy alloy","authors":"Sang Yoon Song ,&nbsp;Tae Jin Jang ,&nbsp;Chang-Gi Lee ,&nbsp;Dae Cheol Yang ,&nbsp;Min Young Sung ,&nbsp;Gunjick Lee ,&nbsp;Jung Hun Han ,&nbsp;Ju-Hyun Baek ,&nbsp;Jin-Yoo Suh ,&nbsp;Alireza Zargaran ,&nbsp;Aparna Saksena ,&nbsp;Baptiste Gault ,&nbsp;Won-Seok Ko ,&nbsp;Se-Ho Kim ,&nbsp;Seok Su Sohn","doi":"10.1016/j.actamat.2026.121972","DOIUrl":"10.1016/j.actamat.2026.121972","url":null,"abstract":"<div><div>Achieving ultrahigh strength in advanced structural materials without compromising their resistance to hydrogen embrittlement (HE) remains a critical challenge. Here, we introduce a design strategy that exploits discontinuous L1₂ precipitation of strengthening particles also boosting HE resistance in a high-entropy alloy. The discontinuous reaction first produces serrated grain boundaries that induce crack deflection at multiple scales, effectively arresting intergranular crack propagation. The precipitates are ordered, coherent L1₂ nanorods with a high hydrogen trapping capability, as revealed by direct isotopically-labelled atom probe measurements and density functional theory calculations, significantly inhibiting hydrogen diffusion. This unique microstructural combination underpins a tensile strength of ∼1.7 GPa with a 33% superior HE resistance compared to a single-phase face-centered cubic reference alloy. Our strategy not only breaks the conventional trade-off between strength and HE, but also delivers higher gains in both tensile strength and HE resistance than conventional approaches, establishing discontinuous L1₂ precipitation as a versatile strategy for designing ultrahigh-strength HE-resistant alloys, with potential applications in hydrogen infrastructure and beyond.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"307 ","pages":"Article 121972"},"PeriodicalIF":9.3,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146072318","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":"Three-dimensional crystallographic and local variant configuration analysis of lath martensite in medium-carbon steel","authors":"Akinobu Shibata ,&nbsp;Goro Miyamoto ,&nbsp;Shigekazu Morito ,&nbsp;Akiko Nakamura ,&nbsp;Taku Moronaga ,&nbsp;Houichi Kitano ,&nbsp;Ivan Gutierrez-Urrutia ,&nbsp;Toru Hara","doi":"10.1016/j.actamat.2026.121981","DOIUrl":"10.1016/j.actamat.2026.121981","url":null,"abstract":"<div><div>The microstructures and crystallographic features of lath martensite in a medium-carbon steel were investigated using focused ion beam-scanning electron microscopy serial sectioning and automated crystallographic orientation mapping in transmission electron microscopy techniques. The analysis revealed that, despite the complex and interwoven overall morphology, individual laths possess well-defined, plate-like shapes. Habit plane / lath boundary plane orientations determined by two-surface trace analysis spanned a range from (2 5 2)_A to (2 9 5)_A in the austenite coordinate system and were centered around (3 8 1)_M in the martensite coordinate system. These results are consistent with predictions from the phenomenological theory of martensitic crystallography incorporating double lattice-invariant deformations and a high degree of tetragonality. Crystallographic variant analysis showed pairing tendencies among variants sharing parallel close-packed planes, along with the presence of nanoscale twin-related domains distinct from typical (1 1 2)_M transformation twins. These domains were interpreted as twin-orientation-related intralath structures that formed ahead of the longitudinal growth front of a martensite plate and were subsequently embedded by its lateral growth. Micromechanics calculations further suggested that stress-induced variant selection, enhanced by high tetragonality, plays a critical role in the preferential formation of these twin-orientation-related intralath structures. Although the lath has traditionally been regarded as the smallest structural unit, detailed characterization of a twin-orientation-related intralath structure reveals an additional level of hierarchy, distinct from conventional defect substructures, fundamentally redefining the established microstructural concept of lath martensite.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"307 ","pages":"Article 121981"},"PeriodicalIF":9.3,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146110040","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":"Insights into the preferential intergranular oxidation mechanism of 316L austenitic stainless steel exposed to oxygen saturated lead-bismuth eutectic (LBE)","authors":"Wenhao Zhang ,&nbsp;Wen Wang ,&nbsp;Jibo Tan ,&nbsp;Xing Gong ,&nbsp;En-Hou Han ,&nbsp;Wenjun Kuang","doi":"10.1016/j.actamat.2026.121962","DOIUrl":"10.1016/j.actamat.2026.121962","url":null,"abstract":"<div><div>The preferential intergranular oxidation (PIO) behavior of 316L stainless steel (SS) exposed to oxygen saturated Lead-bismuth eutectic (LBE) at 550 °C was investigated. PIO occurred at both random high angle grain boundaries (RHABs) and coherent twin boundaries (CTBs), with RHABs exhibiting deeper intergranular oxidation. The high diffusivity of RHAB supports rapid diffusion of Cr toward the PIO front, leading to the formation of extensive polycrystalline Cr₂O₃. In contrast, only a thin flake of Cr₂O₃ was observed at the oxidation front of CTB. Diffusion induced grain boundary migration (DIGM) zones were observed not only at RHAB oxidation front, but also at CTB front. Driven by Ni dissolution through intergranular pores, the DIGM zone further degrades into fragmented Ni-enriched particles along RHAB. Nano-pores, formed via Ni selective leaching and Fe outward diffusion, were observed in intergranular oxides at the oxidation fronts of both RHAB and CTB. These intergranular pores constitute rapid diffusion paths, significantly aggravating PIO.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"307 ","pages":"Article 121962"},"PeriodicalIF":9.3,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146032914","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":"Boosting Strength and ductility of Ti-6Al-4V alloy via millisecond-level electric treatment induced heterogeneous nanostructures","authors":"Jiajun Zhang ,&nbsp;Jiajun Wang ,&nbsp;Yu Yan ,&nbsp;Fei Wang ,&nbsp;Jian Wang ,&nbsp;Jianjiang Zhao ,&nbsp;Yunmin Chen ,&nbsp;Yang Ju ,&nbsp;Hua Wei","doi":"10.1016/j.actamat.2026.121976","DOIUrl":"10.1016/j.actamat.2026.121976","url":null,"abstract":"<div><div>Introducing nanoscale structures into metallic materials is a well-established strategy to achieve a superior strength–ductility balance, yet it often relies on complex, multi-step thermo-mechanical processing. Here, we demonstrate a millisecond-scale electric heating treatment as a simple and effective approach to embed nanostructures in hot-forged Ti-6Al-4V alloys, simultaneously enhancing tensile strength (∼1240.5 MPa) and fracture elongation (∼15.5%). Unlike conventional annealing, the process combines ultrafast localized Joule heating with rapid cooling. The transient high temperatures accelerate short-range elemental diffusion and promote the formation of additional β-Ti clusters. Meanwhile, the brief heating duration suppresses long-range diffusion, stabilizes the α-Ti matrix, and drives the formation of abundant heterogeneous nanostructures. The resulting alternant nanoscale α′-Ti martensite and β-Ti lamellae with distinct misorientations strengthen the alloy, while &lt;<em>c</em>+<em>a</em>&gt;-type dislocations activate at interphase boundaries complement &lt;<em>a</em>&gt;-type slip and enhance plastic flow. Furthermore, localized Joule heating facilitates dislocation depinning and slip transmission, contributing to improved ductility. Overall, ultrafast electric heating provides an effective pathway for integrating nano-lamellar architectures, offering a promising strategy for microstructural engineering in advanced metallic materials.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"307 ","pages":"Article 121976"},"PeriodicalIF":9.3,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146072290","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":"Structural origins of thermal expansion behavior in 2D materials","authors":"Yang Yang ,&nbsp;Guangya Li ,&nbsp;Yixin Lin ,&nbsp;Yan Chen ,&nbsp;Hongxiang Zong ,&nbsp;Xiangdong Ding ,&nbsp;Xun-Li Wang ,&nbsp;Jun Sun","doi":"10.1016/j.actamat.2026.121956","DOIUrl":"10.1016/j.actamat.2026.121956","url":null,"abstract":"<div><div>Two-dimensional (2D) materials exhibit diverse thermal expansion behavior—with coefficients spanning a broad range from negative to positive values—fundamentally challenging our understanding of thermal expansion mechanisms and creating critical uncertainties in thermal stress prediction for next-generation devices. Despite numerous experimental measurements, the fundamental structural mechanisms underlying this remarkable variability remains elusive. Here, we resolve this longstanding puzzle through systematical molecular dynamics simulations of four representative 2D materials: <em>h</em>BN, PbTe, graphene, and MoS₂. Our simulations reveal that thermal expansion behavior is governed by the interplay between the intrinsic chemical bond thermal expansion and out-of-plane structural flexibility. This interplay enables 2D materials to achieve thermal expansion coefficients ranging from -15.0 × 10⁻⁶ K⁻¹ to +52.4 × 10⁻⁶ K⁻¹. Crucially, we demonstrate that thickness and lateral size effects arise exclusively through modulation of out-of-plane deformation freedom, while substrate interactions operate via a dual pathway that simultaneously constrains structural flexibility and modifies intrinsic bond behavior. Our findings culminate in a universal scaling relationship between area-specific bending rigidity and thermal expansion coefficients, providing the first predictive framework for 2D material thermal behavior.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"307 ","pages":"Article 121956"},"PeriodicalIF":9.3,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146014353","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}