Acta Materialia最新文献

{"title":"Influence of isoelectronic mass modulation on phonon decay and transport in layered pnictogen-carbon systems","authors":"Prince Sharma ,&nbsp;Prashant Singh ,&nbsp;Ganesh Balasubramanian","doi":"10.1016/j.actamat.2025.121263","DOIUrl":"10.1016/j.actamat.2025.121263","url":null,"abstract":"<div><div>This study systematically investigates the structural, electronic, and thermal transport properties of layered pnictogen–carbon (Pn₂C₂; Pn = <em>P</em>, As, Sb, Bi) monolayers, revealing a profound influence of isoelectronic mass modulation on phonon dynamics and thermal conductivity. Through first-principles calculations and lattice dynamics analysis, we demonstrate that increasing the atomic mass of pnictogens leads to elongated Pn-C bonds, weakened interatomic interactions, and enhanced phonon-phonon scattering, resulting in a dramatic reduction in lattice thermal conductivity (κ). Specifically, κ decreases exponentially from 65.6 W/m-K in P₂C₂ to an ultralow 0.37 W/m-K in Bi₂C₂, driven by suppressed acoustic-optical phonon gaps <span><math><msubsup><mstyle><mi>Δ</mi></mstyle><mrow><mi>A</mi><mo>−</mo><mi>O</mi></mrow><mstyle><mi>Γ</mi></mstyle></msubsup></math></span>, increased anharmonicity, and reduced phonon lifetimes and group velocities. The transition from semiconducting to metallic behavior in heavier pnictogen-based systems further enhances phonon-electron scattering, contributing to thermal conductivity suppression. Structural analysis highlights the strengthening of out-of-plane C<img>C bonds and the contraction of C<img>Pn<img>C bond angles, which disrupt in-plane phonon transport. These findings establish a design framework for engineering ultralow-κ materials through chemical substitution and structural tuning, offering significant potential for thermoelectric and thermal management applications. This work provides fundamental insights into phonon decay mechanisms and thermal transport in 2D materials, paving the way for advanced phononic and energy-efficient devices.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"296 ","pages":"Article 121263"},"PeriodicalIF":8.3,"publicationDate":"2025-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144288170","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":"Interface strength and crack propagation mechanisms in sintered copper nanoparticles","authors":"Leiming Du ,&nbsp;Weiping Jiao ,&nbsp;Olof Bäcke ,&nbsp;Magnus Hörnqvist Colliander ,&nbsp;René H. Poelma ,&nbsp;Jiajie Fan ,&nbsp;Willem D. van Driel ,&nbsp;Xuejun Fan ,&nbsp;Guoqi Zhang","doi":"10.1016/j.actamat.2025.121187","DOIUrl":"10.1016/j.actamat.2025.121187","url":null,"abstract":"<div><div>This study investigates the interface strength and fracture behavior of sintered copper (Cu) nanoparticles (NPs) for all-Cu integration in advanced microelectronics packaging. Micro-cantilever bending tests on three configurations (Cu NP-notched, interface-notched and un-notched micro-cantilevers) were analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), transmission Kikuchi diffraction (TKD) and cohesive zone model (CZM). The interface-notched micro-cantilevers demonstrate superior fracture resistance, with a stress intensity factor (<span><math><msub><mrow><mi>K</mi></mrow><mrow><mi>Q</mi></mrow></msub></math></span>) of <span><math><mrow><mn>2</mn><mo>.</mo><mn>88</mn><mo>±</mo><mn>0</mn><mo>.</mo><mn>10</mn></mrow></math></span> MPa m<span><math><msup><mrow></mrow><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msup></math></span>, compared to <span><math><mrow><mn>2</mn><mo>.</mo><mn>12</mn><mo>±</mo><mn>0</mn><mo>.</mo><mn>11</mn></mrow></math></span> MPa m<span><math><msup><mrow></mrow><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msup></math></span> for Cu NP-notched micro-cantilevers. Simulation results, consistent with experimental results, reveal that Cu NP-notched micro-cantilevers exhibit lower fracture resistance due to porosity and stress concentrations, while interface-notched micro-cantilevers show enhanced strength, attributed to robust bonding and reduced void distribution. Un-notched micro-cantilevers display superior load-bearing capacity, with cracks bypassing the interface and propagating through porous regions. Moreover, in un-notched micro-cantilevers, a synergistic deformation mechanism is observed, where crack propagation through the sintered Cu NPs coexists with plastic slip deformation in the Cu substrate. These findings highlight the strong interfacial bonding and effective stress transfer at the Cu substrate-sintered Cu NP interface, validating the feasibility of direct sintering using Cu NPs without additional coatings.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"296 ","pages":"Article 121187"},"PeriodicalIF":8.3,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144289139","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":"Mixed ionic and electronic behaviour in SrCo1-xScxO3-δ (x = 0.1 and 0.2) perovskites: novel cathode materials for SOFC","authors":"Vanessa Cascos ,&nbsp;Mónica Chivite-Lacaba ,&nbsp;Jesús Prado-Gonjal ,&nbsp;María Teresa Fernández-Díaz ,&nbsp;José Antonio Alonso","doi":"10.1016/j.actamat.2025.121262","DOIUrl":"10.1016/j.actamat.2025.121262","url":null,"abstract":"<div><div>The oxygen deficient perovskite SrCoO_3-δ could outperform as cathode material in intermediate-temperature solid-oxide fuel cells (IT-SOFC) if a three-dimensional (3C-type) framework were stabilized under the stringent working conditions of SOFC. Here, we demonstrate that the inclusion of moderate amounts of <em>Sc</em> at the octahedral sites leads to the stabilization of a tetragonal <em>P</em>4/<em>mmm</em> perovskite superstructure, where the desired 3C framework is preserved, rather than the undesirable 2H polytype-corresponding hexagonal phase. As SOFC cathodes, we studied the thermal, electrical, and electrochemical characteristics of SrCo_1−xSc_xO_3-δ (<em>x</em> = 0.1 and 0.2) perovskite oxides. These oxides suit the requirements for mixed ionic and electronic conductors (MIEC) oxides because they have a high concentration of oxygen vacancies, strong electrical conductivity, and great thermal stability. With H₂ as fuel and air as the oxidant, single-cell tests for these compositions, in conjunction with La_0.8Sr_0.2Ga_0.83Mg_0.17O_3−δ (LSGM) as electrolyte and SrMo_0.8Fe_0.2O_3−δ as the anode, produce power densities exceeding 700 mW/cm² at 850 °C.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"296 ","pages":"Article 121262"},"PeriodicalIF":8.3,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144288171","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":"Superior strength-plasticity integrated TiAl based alloys relying on the dynamic precipitation phase and crystal orientation evolution","authors":"Kexuan Li ,&nbsp;Hongze Fang ,&nbsp;Xiaokang Yang ,&nbsp;Lingyan Zhou ,&nbsp;Xianfei Ding ,&nbsp;Ruirun Chen","doi":"10.1016/j.actamat.2025.121253","DOIUrl":"10.1016/j.actamat.2025.121253","url":null,"abstract":"<div><div>The precise control of carbides is key factor in improving service performance of TiAl alloys. We reported a dynamic precipitation strategy that endows TiAl alloys with excellent strength and plasticity. Results show that after doping 0.1 at% C, TiAl matrix is refined, without carbide precipitation, and the relative content of β₀ phase is reduced. After tensile test at 800°C, Ti48Al5Nb2Cr0.6Re alloy exhibits softening characteristics of dynamic recrystallization and planar dislocation-slip, while nano Cr-Re phase and Ti₂AlC particles are precipitated in Ti48Al5Nb2Cr0.6Re0.1C alloy. The γ phase, α₂ phase, and Ti₂AlC particle exhibit specific orientation relationship of (111)_γ // (0001}_α2 // (0001)_Ti2AlC and &lt;110&gt;_γ // &lt;11<span><math><mover><mn>2</mn><mo>¯</mo></mover></math></span>0&gt;_α2 // &lt;10<span><math><mover><mn>1</mn><mo>¯</mo></mover></math></span>0&gt;_Ti2AlC. After tensile test at 900°C, Ti48Al5Nb2Cr0.6Re alloy is in the plastic deformation stage, whereas Ti48Al5Nb2Cr0.6Re0.1C alloy begins to transition from brittle to ductile behavior. High-temperature and stress accelerate the diffusion of C, high-density dislocations and mechanical twinning provide rapid pathways for Ti₂AlC precipitation. Nano precipitates and unique (0001)_Ti2AlC texture evolution retard the softening of Ti48Al5Nb2Cr0.6Re0.1C alloy. As temperature increases from 750 to 900°C, the tensile properties of Ti48Al5Nb2Cr0.6Re alloy decrease from 594MPa and 4.11% to 440MPa and 10.51%, while that of Ti48Al5Nb2Cr0.6Re0.1C alloy first increase from 493MPa and 2.23% to 722MPa and 4.41%, and then stabilize above 520MPa with more than 8% elongation. The improvement in tensile properties is attributed to the reduction of β₀ phase, refinement of microstructure, the interaction between nano Cr-Re phase and dislocations, and the dynamic precipitation of nano Ti₂AlC particles.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"296 ","pages":"Article 121253"},"PeriodicalIF":8.3,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144289923","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":"Grain size dependent martensitic twinning behavior in superelastic Ti-20Zr-12Nb-2Sn alloy: A comparative study","authors":"J.J. Gao ,&nbsp;P. Castany ,&nbsp;T. Gloriant","doi":"10.1016/j.actamat.2025.121260","DOIUrl":"10.1016/j.actamat.2025.121260","url":null,"abstract":"<div><div>The superelastic Ti-20Zr-12Nb-2Sn (at. %) alloy is investigated before and after deformation by cyclic/conventional tensile tests, optical microscopy, <em>in situ</em> synchrotron X-ray diffraction (SXRD), electron back-scattered diffraction (EBSD) and transmission electron microscopy (TEM) after 700 °C and 900 °C solution treatments for 30 min. Both of the specimens show the same {111}&lt;101&gt;_β recrystallization texture, but a different average grain size of respectively 8 μm and 105 μm. Occurrence of the reversible stress-induced martensitic (SIM) α\" transformation is validated through <em>in situ</em> SXRD. After plastic deformation, this alloy displays a grain size dependent martensitic twinning behavior. In the fine grain material, only residual SIM α\" phase is observed with no twinning up to rupture, which was never reported in plastically deformed Ti-based superelastic alloys. In the coarse grain material, twins are observed in residual SIM α\" phase. For the 5 % strained specimen, primary/secondary martensitic α\" band undergoes a novel three-step twinning process (primary {130}&lt;310&gt;_α\" twinning + &lt;211&gt;_α\" type II twinning + secondary {130}&lt;310&gt;_α\" twinning). We also showed that the final product of this three-step process can be misinterpreted as {021}&lt;512&gt;_α\" type II twinning. This primary/secondary α\" twin band is then further partially twinned again by a third {130}&lt;310&gt;_α\" twinning or {110}&lt;110&gt;_α\" twinning at 8 % of strain, highlighting an unprecedented fourth step twinning process. {130}&lt;310&gt;_α\" twins are systematically reorientated by &lt;211&gt;_α\" type II twinning in order to maximize the transformation strain value with respect to their β phase counterpart. This work comprehensively sheds light on the mechanism of superelasticity optimization via grain size refinement strategy.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"296 ","pages":"Article 121260"},"PeriodicalIF":8.3,"publicationDate":"2025-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144322877","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":"Enhanced mechanical performance of HoB2-based compounds without sacrificing cryogenic magnetocaloric effects","authors":"Zexuan Wang ,&nbsp;A.M. Döring ,&nbsp;O. Vasylkiv ,&nbsp;Xin Tang ,&nbsp;K.P. Skokov ,&nbsp;N. Terada ,&nbsp;T. Ohkubo ,&nbsp;O. Gutfleisch ,&nbsp;H. Sepehri-Amin","doi":"10.1016/j.actamat.2025.121227","DOIUrl":"10.1016/j.actamat.2025.121227","url":null,"abstract":"<div><div>Cryogenic magnetic cooling based on magnetocaloric effect is a promising technology for green and efficient hydrogen gas liquefaction. One of the major challenges for practical application is the lack of magnetocaloric materials that exhibit excellent cyclic performance in both magnetocaloric properties and fracture toughness. HoB₂, an intermetallic compound, exhibits a giant magnetocaloric effect, but its brittleness under mechanical stress hinders practical applications. In this work, we report a 12-fold increase in the fracture toughness by doping 10 at. % Cu into the HoB₂ system, from 2.6 to 35.1 MPa·m^1/2. Vickers indentation tests followed by the microstructural evaluation revealed that the formation of (Ho, Cu)-rich intergranular phases with a fine distribution in the microstructure, encircling HoB₂, suppresses the propagation of initiated cracks in HoB₂-based compounds, thereby improving their fracture toughness. In the 10 at. % Cu-doped sample, a (Ho, Cu)-rich intergranular phase was formed with an areal fraction of ∼18 %, while the content of the secondary HoB₄ phase, commonly observed in the Cu-free sample, was reduced. Notably, no Cu dissolution was found in the matrix phase. The fracture toughness improved significantly with minimal impact on magnetocaloric performance: the isothermal field-induced entropy change (Δ<em>S_T</em>) was marginally reduced from 20.1 to 18.2 J kg⁻¹ K⁻¹_, and the adiabatic temperature change (∆<em>T</em>_ad) from 5.1 to 4.7 K in a 2 T magnetic field. The physical property analysis revealed that the sample containing the (Ho, Cu)-rich intergranular phase has lower magnetostriction, which can extend the life of the material in practical applications by reducing internal stress.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"296 ","pages":"Article 121227"},"PeriodicalIF":8.3,"publicationDate":"2025-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144268923","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":"Probing nanoscale variant distribution in a heterogenous α/β titanium alloy","authors":"Yandi Jia ,&nbsp;Yingjie Ma ,&nbsp;Rongpei Shi ,&nbsp;Yuexin Zhou ,&nbsp;Qian Wang ,&nbsp;Sensen Huang ,&nbsp;Min Qi ,&nbsp;Dong Wang ,&nbsp;Jiafeng Lei ,&nbsp;Rui Yang","doi":"10.1016/j.actamat.2025.121148","DOIUrl":"10.1016/j.actamat.2025.121148","url":null,"abstract":"<div><div>In titanium alloys, engineering highly heterogeneous <em>α</em>-phase precipitate microstructure—comprising micron-scale primary <em>α</em> and nano-scale secondary <em>α</em> precipitates—offers a promising strategy to bypass the strength-ductility trade-off. Beyond classical microstructure descriptors (e.g., volume fraction, size, shape, orientation, coherency state, and spatial distribution), the variant distribution of precipitates crucially governs mechanical properties. However, the variant distribution behavior remains poorly understood for super-refined <em>α</em> precipitate (<span><math><mrow><mo>&lt;</mo><mn>100</mn><mspace></mspace><mtext>nm</mtext></mrow></math></span>). For the first time, this work systematically investigates the size-dependent variant distribution of <em>α</em> precipitates in an <em>α</em>/<em>β</em> Ti alloy by integrating Transmission Kikuchi Diffraction (TKD) characterization and crystallographic analysis. Notably, inter-variant misorientation is quantified using misorientation axis analysis rather than conventional angular thresholds. A precipitate size-dependent variant distribution is identified, where the spatial correlation and occurrence frequency of <em>α</em> variants linked by the Type B misorientation axis-angle pair <span><math><mrow><msub><mrow><mo>[</mo><mover><mrow><mn>1</mn></mrow><mo>‾</mo></mover><mn>2</mn><mover><mrow><mn>1</mn></mrow><mo>‾</mo></mover><mn>0</mn><mo>]</mo></mrow><mi>α</mi></msub><mo>/</mo><mn>60.0</mn><mtext>°</mtext></mrow></math></span> strengthens as precipitate size decreases. These experimental observations are validated through phase-field simulations that generate <em>α</em> precipitates with varying sizes and number densities. Mechanistic analysis reveals that finer <em>α</em> precipitates, formed via an <em>ω</em>-assisted nucleation mechanism, amplify elastic interactions that promote strain-induced correlated nucleation, driving the stronger preference of Type B inter-variant correlations. The study provides crucial insights into the distribution and characteristics of the super-refined <em>α</em> phase in titanium alloys and may contribute to the understanding of deformation mechanism of the highly heterogeneous precipitate microstructure.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"296 ","pages":"Article 121148"},"PeriodicalIF":8.3,"publicationDate":"2025-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144263723","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":"Glass formation during combinatorial sputtering in binary alloys","authors":"Salena Huang ,&nbsp;Sebastian A. Kube ,&nbsp;Nathan S. Johnson ,&nbsp;Sungwoo Sohn ,&nbsp;Apurva Mehta ,&nbsp;Jan Schroers","doi":"10.1016/j.actamat.2025.121240","DOIUrl":"10.1016/j.actamat.2025.121240","url":null,"abstract":"<div><div>Glass formation is a complex phenomenon influenced by thermodynamic and kinetic aspects, which are often controlled by extrinsic contributions. While bulk metallic glasses are typically multicomponent alloys, binary alloys offer a simplified approach to studying glass formation. In this study, we fabricated 57 binary alloy systems through combinatorial sputtering, where each alloy system is represented in 66 different alloys. We developed an automated analysis to determine structure and composition using X-ray diffraction and energy-dispersive X-ray spectroscopy for over 3700 alloys. We found that ∼17 % of the alloys form glasses under the estimated cooling rate during sputtering of ∼10⁸ K/s. Data analysis revealed that commonly used factors like atomic size ratio and heat of mixing are ineffective in predicting glass formation. However, the crystal structure mismatch of the alloys’ elements emerged as the strongest indicator of glass formation under sputtering conditions of binary alloys. The differences in glass formation under slow cooling rates used for bulk glass formation and the here observed glass formation under rapid cooling rates are discussed.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"296 ","pages":"Article 121240"},"PeriodicalIF":8.3,"publicationDate":"2025-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144269149","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":"Temperature-dependent interplay of intra- and inter-granular deformation mechanisms in Mg-10Y: Statistical analysis from an HRDIC perspective","authors":"Ran Ni ,&nbsp;Carl J. Boehlert ,&nbsp;Bo Chen ,&nbsp;Yuanshuai Zhang ,&nbsp;Ying Zeng ,&nbsp;Jiang Zheng ,&nbsp;Hao Zhou ,&nbsp;Qudong Wang ,&nbsp;Dongdi Yin","doi":"10.1016/j.actamat.2025.121256","DOIUrl":"10.1016/j.actamat.2025.121256","url":null,"abstract":"<div><div>To uncover the anomalous temperature-dependent slip activity (decreased non-basal slip activity with increasing temperature) in polycrystalline Mg-10Y (wt. %) during compression, the deformation mode activity was quantitatively investigated using high-resolution digital image correlation (HRDIC) and electron backscattered diffraction (EBSD) data fusion. The deformed microstructural patches that were characterized contained ∼300 grains and ∼800 grain boundaries (GBs), and ∼45 million measured strain data were acquired to statistically interrogate both intra- and inter-granular mechanisms. From a strain-partitioning perspective, the competition between slip bands (SBs) and grain mantles (GMs, the region near GBs) was quantified. At 25 °C, the SB deformation, in terms of the mean effective shear strain ratio (SR), was ∼2.5 times greater than that of the GM. As temperature increased (up to 300 °C), the SR discrepancy between the SB and the GM decreased significantly. The prevalent SB mode transitioned from multiple slip at 25–200 °C to single slip at 300 °C. Basal slip was dominant at 25 °C and the percentage of non-basal slip increased from 22.4% at 25 °C to 41.5% at 200 °C and then it anomalously decreased to 10.6% at 300 °C. At 300 °C, the surface GB sliding (GBS) increased significantly compared to that at 25 °C, with mean value of the GBS displacements increasing from 1.2±7.8 to 18.3±27.9 nm and the percentage of GBs in which displacements were observed increased from 4.2% to 53.9%. This work emphasizes the importance of simultaneously evaluating both intra- and inter-granular deformation mechanisms for polycrystalline microstructures.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"296 ","pages":"Article 121256"},"PeriodicalIF":8.3,"publicationDate":"2025-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144268922","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":"Nanoscale mechanisms limiting non-basal plasticity in magnesium","authors":"Jiwon Jeong ,&nbsp;Zhuocheng Xie ,&nbsp;Markus Alfreider ,&nbsp;Sandra Korte-Kerzel ,&nbsp;Daniel Kiener ,&nbsp;Julien Guénolé ,&nbsp;Sang Ho Oh","doi":"10.1016/j.actamat.2025.121261","DOIUrl":"10.1016/j.actamat.2025.121261","url":null,"abstract":"<div><div>Dislocations of the <span><math><mrow><mo>〈</mo><mi>c</mi></mrow></math></span>+<span><math><mrow><mi>a</mi><mo>〉</mo></mrow></math></span> type are widely recognized as the primary defects limiting the ductility of magnesium. While their glide can be activated in small magnesium crystals under high flow stresses, our in-situ transmission electron microscopy compression tests, conducted over a large strain range, reveal that <span><math><mrow><mo>〈</mo><mi>c</mi></mrow></math></span>+<span><math><mrow><mi>a</mi><mo>〉</mo></mrow></math></span> dislocation plasticity becomes inactive following initial activation, leading to dislocation avalanches and subsequent deformation twinning. Initially, pyramidal II slip mediated by <span><math><mrow><mo>〈</mo><mi>c</mi></mrow></math></span>+<span><math><mrow><mi>a</mi><mo>〉</mo></mrow></math></span> dislocations accommodates plastic deformation in <em>c</em>-axis-oriented magnesium pillars under compression. However, as deformation progresses, interactions among dislocations increasingly impede further glide and prevent surface annihilation. Correlative atomistic simulations indicate that this limited dislocation plasticity arises from the formation of basal <em>I</em>₁ and <em>I</em>₂ stacking faults, generated by interactions between glissile pyramidal II dislocations. The restricted motion of <span><math><mrow><mo>〈</mo><mi>c</mi></mrow></math></span>+<span><math><mrow><mi>a</mi><mo>〉</mo></mrow></math></span> dislocations consequently results in stress accumulation, which triggers dislocation avalanches and deformation twinning. This deformation behavior fundamentally differs from the typical dislocation starvation or exhaustion mechanisms observed in small-scale plasticity, offering novel insights into plasticity and work hardening in bulk magnesium.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"296 ","pages":"Article 121261"},"PeriodicalIF":8.3,"publicationDate":"2025-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144490154","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}