Pub Date : 2026-01-13DOI: 10.1016/j.actamat.2026.121929
Hye-Hyun Ahn , Jae Hur , Guanglong Xu , Won-Seok Ko
Mg–Sc shape memory alloys exhibit exceptionally low density but suffer from very low transformation temperatures. Here, we combine first-principles calculations, phonon analysis, molecular dynamics simulations, and hybrid Monte Carlo/molecular dynamics to uncover the atomic-scale mechanisms governing phase transformations in Mg–Sc alloys. Our results reveal that partial atomic ordering is essential for reversible martensitic transformations, with partially ordered B2 austenite and B19 martensite structures being thermodynamically favored over their disordered counterparts across compositions of 15–25 at.% Sc. This ordered transformation pathway exhibits remarkable composition sensitivity: reducing Sc content progressively stabilizes martensite relative to austenite, driving increases in the transformation temperature consistent with reported experimental trends. This comprehensive atomistic understanding provides a clear strategy for developing ambient-temperature lightweight SMAs through compositional optimization and controlled ordering.
{"title":"Atomistic insights into structural ordering effects on martensitic transformations in Mg–Sc shape memory alloys","authors":"Hye-Hyun Ahn , Jae Hur , Guanglong Xu , Won-Seok Ko","doi":"10.1016/j.actamat.2026.121929","DOIUrl":"10.1016/j.actamat.2026.121929","url":null,"abstract":"<div><div>Mg–Sc shape memory alloys exhibit exceptionally low density but suffer from very low transformation temperatures. Here, we combine first-principles calculations, phonon analysis, molecular dynamics simulations, and hybrid Monte Carlo/molecular dynamics to uncover the atomic-scale mechanisms governing phase transformations in Mg–Sc alloys. Our results reveal that partial atomic ordering is essential for reversible martensitic transformations, with partially ordered B2 austenite and B19 martensite structures being thermodynamically favored over their disordered counterparts across compositions of 15–25 at.% Sc. This ordered transformation pathway exhibits remarkable composition sensitivity: reducing Sc content progressively stabilizes martensite relative to austenite, driving increases in the transformation temperature consistent with reported experimental trends. This comprehensive atomistic understanding provides a clear strategy for developing ambient-temperature lightweight SMAs through compositional optimization and controlled ordering.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"306 ","pages":"Article 121929"},"PeriodicalIF":9.3,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145962468","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}
Pub Date : 2026-01-13DOI: 10.1016/j.actamat.2025.121878
Francesco Aiello , Jian Zhang , Johannes C. Brouwer , Michele Cassetta , Mauro Salazar , Diletta Giuntini
An optimization-driven approach is presented to create a “double-tough” ceramic. The material features two main toughening mechanisms – crack deflection in a brick-and-mortar microstructure, and transformation toughening in the mortar – and it is engineered to achieve high strength and fracture toughness levels simultaneously. The material design involves high-strength alumina bricks interconnected via a ceria-stabilized zirconia mortar. Given that the design of the optimal material, featuring multiscale toughening mechanisms, typically requires a laborious trial-and-error approach, a Bayesian optimization framework is proposed to streamline and accelerate the experimental campaign. A Gaussian process is used to emulate the material’s mechanical response, and a cost-aware batch Bayesian optimization is implemented to efficiently identify optimal design process parameters, accounting for the cost of experimentally varying them. This approach expedites the optimization of the material’s mechanical properties. As a result, a bio-inspired all-ceramic composite is developed, exhibiting an exceptional balance between bending strength () and fracture toughness (m), along with a stress intensity factor at crack initiation of m. The material exhibits significantly higher strength than both nacre-like ceramic composites and transformation-toughened zirconia at comparable toughness levels.
{"title":"Double-tough and ultra-strong ceramics: Leveraging multiscale toughening mechanisms through Bayesian optimization","authors":"Francesco Aiello , Jian Zhang , Johannes C. Brouwer , Michele Cassetta , Mauro Salazar , Diletta Giuntini","doi":"10.1016/j.actamat.2025.121878","DOIUrl":"10.1016/j.actamat.2025.121878","url":null,"abstract":"<div><div>An optimization-driven approach is presented to create a “double-tough” ceramic. The material features two main toughening mechanisms – crack deflection in a brick-and-mortar microstructure, and transformation toughening in the mortar – and it is engineered to achieve high strength and fracture toughness levels simultaneously. The material design involves high-strength alumina bricks interconnected via a ceria-stabilized zirconia mortar. Given that the design of the optimal material, featuring multiscale toughening mechanisms, typically requires a laborious trial-and-error approach, a Bayesian optimization framework is proposed to streamline and accelerate the experimental campaign. A Gaussian process is used to emulate the material’s mechanical response, and a cost-aware batch Bayesian optimization is implemented to efficiently identify optimal design process parameters, accounting for the cost of experimentally varying them. This approach expedites the optimization of the material’s mechanical properties. As a result, a bio-inspired all-ceramic composite is developed, exhibiting an exceptional balance between bending strength (<span><math><mrow><mn>704</mn><mspace></mspace><mi>MPa</mi></mrow></math></span>) and fracture toughness (<span><math><mrow><mn>13</mn><mo>.</mo><mn>6</mn><mspace></mspace><mi>MPa</mi><mspace></mspace></mrow></math></span>m<span><math><msup><mrow></mrow><mrow><mn>0</mn><mo>.</mo><mn>5</mn></mrow></msup></math></span>), along with a stress intensity factor at crack initiation of <span><math><mrow><mn>6</mn><mo>.</mo><mn>7</mn><mspace></mspace><mi>MPa</mi><mspace></mspace></mrow></math></span>m<span><math><msup><mrow></mrow><mrow><mn>0</mn><mo>.</mo><mn>5</mn></mrow></msup></math></span>. The material exhibits significantly higher strength than both nacre-like ceramic composites and transformation-toughened zirconia at comparable toughness levels.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"306 ","pages":"Article 121878"},"PeriodicalIF":9.3,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145962467","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}
Pub Date : 2026-01-13DOI: 10.1016/j.actamat.2026.121930
Siyuan Cheng, Wang Yi, Mingzong Zhang, Tianchuang Gao, Lijun Zhang
Realizing theoretical alloy composition design is one of the ultimate goals in the field of materials science. While forward and inverse design are two primary methodological approaches, they are typically employed in isolation, and their consistency remains an open question. In this paper, a systematically comparative study on the two strategies in Al-Si-Mg-Cu alloys was performed by integrating computational thermodynamics and active learning approaches to target peak comprehensive mechanical properties. First, the thermodynamic database for the Al-Si-Mg-Cu system was constructed to elucidate the microstructure evolution of Cu-modified Al-8Si-0.4Mg alloys. The optimal Cu content for peak properties was argued through forward design by considering the qualitative link between microstructure and mechanical properties. Subsequently, the predicted microstructures combined with experimental mechanical properties formed the dataset for the active learning model to quantify microstructure-property relationships. Experimental validation and iterative optimization then enhanced the strength-ductility balance. Both design approaches converged on an Al-8Si-0.4Mg-0.62Cu alloy with peak comprehensive mechanical properties. The enhancement in strength is attributed to the formation of Q-Al5Cu2Mg8Si6 and θ-Al2Cu phases, while the reduced ductility results from the brittle θ-Al2Cu phase segregating along the (Al) grain boundaries. Finally, the advantages and limitations of each design strategy, and their combination, are discussed. Integrating forward and inverse design forms a closed-loop rational framework that synergizes physical modeling with data-driven optimization, thereby enhancing the robustness and interpretability of alloy development.
{"title":"Forward versus inverse design of Al-Si-Mg-Cu alloys targeting peak comprehensive mechanical properties: A comparative study integrating computational thermodynamics and active learning","authors":"Siyuan Cheng, Wang Yi, Mingzong Zhang, Tianchuang Gao, Lijun Zhang","doi":"10.1016/j.actamat.2026.121930","DOIUrl":"10.1016/j.actamat.2026.121930","url":null,"abstract":"<div><div>Realizing theoretical alloy composition design is one of the ultimate goals in the field of materials science. While forward and inverse design are two primary methodological approaches, they are typically employed in isolation, and their consistency remains an open question. In this paper, a systematically comparative study on the two strategies in Al-Si-Mg-Cu alloys was performed by integrating computational thermodynamics and active learning approaches to target peak comprehensive mechanical properties. First, the thermodynamic database for the Al-Si-Mg-Cu system was constructed to elucidate the microstructure evolution of Cu-modified Al-8Si-0.4Mg alloys. The optimal Cu content for peak properties was argued through forward design by considering the qualitative link between microstructure and mechanical properties. Subsequently, the predicted microstructures combined with experimental mechanical properties formed the dataset for the active learning model to quantify microstructure-property relationships. Experimental validation and iterative optimization then enhanced the strength-ductility balance. Both design approaches converged on an Al-8Si-0.4Mg-0.62Cu alloy with peak comprehensive mechanical properties. The enhancement in strength is attributed to the formation of Q-Al<sub>5</sub>Cu<sub>2</sub>Mg<sub>8</sub>Si<sub>6</sub> and θ-Al<sub>2</sub>Cu phases, while the reduced ductility results from the brittle θ-Al<sub>2</sub>Cu phase segregating along the (Al) grain boundaries. Finally, the advantages and limitations of each design strategy, and their combination, are discussed. Integrating forward and inverse design forms a closed-loop rational framework that synergizes physical modeling with data-driven optimization, thereby enhancing the robustness and interpretability of alloy development.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"306 ","pages":"Article 121930"},"PeriodicalIF":9.3,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145962470","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}
Pub Date : 2026-01-12DOI: 10.1016/j.actamat.2026.121927
Rubayet Tanveer , Dylan Windsor , Cale Overstreet , Tatenda Kanyowa , Bin Hu , Maik K. Lang , Haixuan Xu , Veerle Keppens , William J. Weber
Two entropy-enriched garnet compositions Y3Fe4(ScCrGaAl)1O12 and Y3Fe3(ScCrGaAl)2O12 were synthesized via the substitution on the Fe3+ sublattice in yttrium iron garnet (YIG). Structural characterization via X-ray diffraction (XRD) and Raman spectroscopy confirmed that both materials retain the cubic garnet phase with space group Ia̅3d. To unravel local structural features, synchrotron X-ray pair distribution function (PDF) analysis was performed using relaxed randomly generated structures. These fits reveal that the local site preference of the substituent cations – particularly their occupation of tetrahedral vs. octahedral coordination – govern their characteristic cation-oxygen bond length distributions. The data further support a strong site selectivity for Sc³⁺ and Cr³⁺ toward the larger octahedral environments, likely driven by their ionic radii and crystal field stabilization energies. Strikingly, in the Y3Fe4(ScCrGaAl)1O12 composition, the PDF analysis also uncovered a local order, interpreted as Al3+ ions predominantly occupying the tetrahedral sites – a feature remained invisible to both XRD and Raman methods. This local order appears to disrupt long-range magnetic connectivity, fostering spin chain fragmentation and resulting in cluster-glass-like magnetic behavior. Photoluminescence measurements reveal that the incorporation of Cr³⁺ significantly enhances emission intensity with the emergence of local structural ordering partially delocalizing the crystal-field environment.
{"title":"Decoding the role of short-range structural order on magnetic and luminescent properties in entropy-enriched yttrium iron garnets","authors":"Rubayet Tanveer , Dylan Windsor , Cale Overstreet , Tatenda Kanyowa , Bin Hu , Maik K. Lang , Haixuan Xu , Veerle Keppens , William J. Weber","doi":"10.1016/j.actamat.2026.121927","DOIUrl":"10.1016/j.actamat.2026.121927","url":null,"abstract":"<div><div>Two entropy-enriched garnet compositions Y<sub>3</sub>Fe<sub>4</sub>(ScCrGaAl)<sub>1</sub>O<sub>12</sub> and Y<sub>3</sub>Fe<sub>3</sub>(ScCrGaAl)<sub>2</sub>O<sub>12</sub> were synthesized via the substitution on the <em>Fe<sup>3+</sup></em> sublattice in yttrium iron garnet (YIG). Structural characterization via X-ray diffraction (XRD) and Raman spectroscopy confirmed that both materials retain the cubic garnet phase with space group <em>Ia̅3d</em>. To unravel local structural features, synchrotron X-ray pair distribution function (PDF) analysis was performed using relaxed randomly generated structures. These fits reveal that the local site preference of the substituent cations – particularly their occupation of tetrahedral vs. octahedral coordination – govern their characteristic cation-oxygen bond length distributions. The data further support a strong site selectivity for <em>Sc³⁺</em> and <em>Cr³⁺</em> toward the larger octahedral environments, likely driven by their ionic radii and crystal field stabilization energies. Strikingly, in the Y<sub>3</sub>Fe<sub>4</sub>(ScCrGaAl)<sub>1</sub>O<sub>12</sub> composition, the PDF analysis also uncovered a local order, interpreted as <em>Al<sup>3+</sup></em> ions predominantly occupying the tetrahedral sites – a feature remained invisible to both XRD and Raman methods. This local order appears to disrupt long-range magnetic connectivity, fostering spin chain fragmentation and resulting in cluster-glass-like magnetic behavior. Photoluminescence measurements reveal that the incorporation of <em>Cr³⁺</em> significantly enhances emission intensity with the emergence of local structural ordering partially delocalizing the crystal-field environment.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"306 ","pages":"Article 121927"},"PeriodicalIF":9.3,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145956729","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}
Pub Date : 2026-01-12DOI: 10.1016/j.actamat.2026.121926
Alexandre P. Solomon , Eric C. O’Quinn , Cale C. Overstreet , Pascal Simon , Christina Trautmann , Changyong Park , David Sprouster , Gianguido Baldinozzi , Maik K. Lang
The radiation-induced monoclinic-to-tetragonal phase transition in ZrO2 and HfO2 has been the subject of many investigations, but the transformation pathways and underlying structural mechanisms are still not well understood. In this study, microcrystalline powder samples of ZrO2 and HfO2 were irradiated with 946 MeV and 1470 MeV Au ions to a wide fluence range up to 3 × 1013 ions/cm2. To characterize beam-induced structural modifications across all spatial length scales, complementary experimental techniques such as synchrotron X-ray diffraction and spallation neutron total scattering were used. The phase evolution of the tetragonal polymorph with increasing ion fluence is accurately described by a heterogeneous track-overlap model that incorporates both direct- and double-impact processes. These damage accumulation processes are an expression of a core-shell ion track morphology that depends on irradiation conditions and target material. Neutron pair distribution function analysis revealed that ion-beam-induced tetragonal ZrO2 is merely a configurational average of short-range orthorhombic (Pbcn) domains stabilized by a dense network of domain walls. This knowledge is critical for a better understanding of how crystalline-to-crystalline phase transformations proceed at the atomic scale under extreme conditions.
{"title":"Multi-scale structural analysis of swift heavy ion-irradiated ZrO2 and HfO2","authors":"Alexandre P. Solomon , Eric C. O’Quinn , Cale C. Overstreet , Pascal Simon , Christina Trautmann , Changyong Park , David Sprouster , Gianguido Baldinozzi , Maik K. Lang","doi":"10.1016/j.actamat.2026.121926","DOIUrl":"10.1016/j.actamat.2026.121926","url":null,"abstract":"<div><div>The radiation-induced monoclinic-to-tetragonal phase transition in ZrO<sub>2</sub> and HfO<sub>2</sub> has been the subject of many investigations, but the transformation pathways and underlying structural mechanisms are still not well understood. In this study, microcrystalline powder samples of ZrO<sub>2</sub> and HfO<sub>2</sub> were irradiated with 946 MeV and 1470 MeV Au ions to a wide fluence range up to 3 × 10<sup>13</sup> ions/cm<sup>2</sup>. To characterize beam-induced structural modifications across all spatial length scales, complementary experimental techniques such as synchrotron X-ray diffraction and spallation neutron total scattering were used. The phase evolution of the tetragonal polymorph with increasing ion fluence is accurately described by a heterogeneous track-overlap model that incorporates both direct- and double-impact processes. These damage accumulation processes are an expression of a core-shell ion track morphology that depends on irradiation conditions and target material. Neutron pair distribution function analysis revealed that ion-beam-induced tetragonal ZrO<sub>2</sub> is merely a configurational average of short-range orthorhombic (<em>Pbcn</em>) domains stabilized by a dense network of domain walls. This knowledge is critical for a better understanding of how crystalline-to-crystalline phase transformations proceed at the atomic scale under extreme conditions.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"306 ","pages":"Article 121926"},"PeriodicalIF":9.3,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145956678","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}
Pub Date : 2026-01-11DOI: 10.1016/j.actamat.2026.121923
Kamila Hamulka , Tijmen Vermeij , Amit Sharma , Renato Pero , Johann Michler , Xavier Maeder
The plastic deformation behavior of high-purity alpha-titanium (α-Ti) single crystals is investigated through micropillar compression experiments over a wide range of strain rates at room temperature. For c - axis compression, where prismatic slip is geometrically unfavorable, two distinct deformation regimes emerge. At low to intermediate strain rates plasticity is governed by a non-classical kink band-type mechanism. Deformation is accommodated within broad, localized bands exhibiting significant continuous lattice rotation and internal dislocation structures. These bands lack discrete slip traces and show features distinct from conventional slip or twinning. At higher strain rates a transition to deformation twinning is observed, characterized by exhaustive twinning and twin-twin interactions. This shift in deformation mode coincides with a notable increase in flow stress. In contrast, for compression perpendicular to the c - axis, plastic deformation is consistently accommodated by prismatic slip across the entire range of strain rates, without showing any evidence of twinning or kink band formation. Additionally, the flow stress is significantly (7x) lower than that under c - axis loading. This work provides direct experimental evidence of strain rate-induced transitions in deformation mechanisms of α-Ti at the microscale.
{"title":"Effects of strain rate and c-axis orientation on microscale α-Ti compression: From kink bands to twinning","authors":"Kamila Hamulka , Tijmen Vermeij , Amit Sharma , Renato Pero , Johann Michler , Xavier Maeder","doi":"10.1016/j.actamat.2026.121923","DOIUrl":"10.1016/j.actamat.2026.121923","url":null,"abstract":"<div><div>The plastic deformation behavior of high-purity alpha-titanium (α-Ti) single crystals is investigated through micropillar compression experiments over a wide range of strain rates <span><math><mrow><mo>(</mo><mrow><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>3</mn><mspace></mspace></mrow></msup><mtext>to</mtext><mspace></mspace><msup><mrow><mn>10</mn></mrow><mn>3</mn></msup><mspace></mspace><msup><mrow><mi>s</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow><mo>)</mo></mrow></math></span> at room temperature. For <em>c</em> - axis compression, where prismatic slip is geometrically unfavorable, two distinct deformation regimes emerge. At low to intermediate strain rates <span><math><mrow><mo>(</mo><mover><mrow><mi>ε</mi></mrow><mi>˙</mi></mover><mo><</mo><msup><mrow><mn>10</mn></mrow><mn>2</mn></msup><mspace></mspace><msup><mrow><mi>s</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup><mo>)</mo></mrow></math></span> plasticity is governed by a non-classical kink band-type mechanism. Deformation is accommodated within broad, localized bands exhibiting significant continuous lattice rotation and internal <span><math><mrow><mo>〈</mo><mrow><mi>c</mi><mo>+</mo><mi>a</mi></mrow><mo>〉</mo><mspace></mspace></mrow></math></span> dislocation structures. These bands lack discrete slip traces and show features distinct from conventional slip or twinning. At higher strain rates <span><math><mrow><mo>(</mo><mrow><mover><mrow><mi>ε</mi></mrow><mi>˙</mi></mover><mo>≥</mo><msup><mrow><mn>10</mn></mrow><mn>2</mn></msup><mspace></mspace><msup><mrow><mi>s</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow><mo>)</mo></mrow></math></span> a transition to deformation twinning is observed, characterized by exhaustive <span><math><mrow><mrow><mo>{</mo><mrow><mn>11</mn><mover><mn>2</mn><mo>¯</mo></mover><mn>2</mn></mrow><mo>}</mo></mrow><mrow><mo>〈</mo><mrow><mover><mn>1</mn><mo>¯</mo></mover><mover><mn>1</mn><mo>¯</mo></mover><mn>23</mn></mrow><mo>〉</mo></mrow></mrow></math></span> twinning and twin-twin interactions. This shift in deformation mode coincides with a notable increase in flow stress. In contrast, for compression perpendicular to the <em>c</em> - axis, plastic deformation is consistently accommodated by prismatic <span><math><mrow><mrow><mo>{</mo><mrow><mn>10</mn><mover><mn>1</mn><mo>¯</mo></mover><mn>0</mn></mrow><mo>}</mo></mrow><mrow><mo>〈</mo><mrow><mn>11</mn><mover><mn>2</mn><mo>¯</mo></mover><mn>0</mn></mrow><mo>〉</mo></mrow></mrow></math></span> slip across the entire range of strain rates, without showing any evidence of twinning or kink band formation. Additionally, the flow stress is significantly (7x) lower than that under <em>c</em> - axis loading. This work provides direct experimental evidence of strain rate-induced transitions in deformation mechanisms of α-Ti at the microscale.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"306 ","pages":"Article 121923"},"PeriodicalIF":9.3,"publicationDate":"2026-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145956470","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}
Pub Date : 2026-01-11DOI: 10.1016/j.actamat.2026.121909
Bo Li , Chenhui Hu , Kaiyuan Shi , Lei Su , Yizhe Cao , Huiying Liu , Dongxu Hui , Shaodi Wang , Chuanwei Fan , Katsuyoshi Kondoh , Xin Zhang , Shengyin Zhou , Shufeng Li
Deviatoric stress and microstructural imperfections are considered the main reasons for the promotion of phase transformation (PT) of metals at high pressure. However, structural heterogeneity induced by secondary phases will pose challenges for understanding the high-pressure deformation and PT of metallic composites. For instance, anomalies related to kinetic suppression were observed in the forward (α→ω) and reverse (ω→α) transformation of α-Ti confined by TiB upon nonhydrostatic pressure. Here, static/dynamic diamond anvil cells and synchrotron X-ray diffraction were utilized to panoramically resolve the dislocation evolution in plastic flow deformation and strain-induced PT of Ti-TiB microcomposite. Diffraction peak profile analysis reveals a decrease in dislocation density of confined α-Ti from plastic flow (1×1016 m−2) to strain-induced PT (6.7×1015 m−2), accompanied with the activation of ∼60% <a> slip systems and a varying combination of <c> and <c+a>. Long-range internal stress at Ti/TiB interface increases quasi-linearly to a maximum accounting for ∼17% of total pressure as the nonhydrostatic pressure increases. It probably indicates the key role of heterogeneous-stress-partition in lowering local stress required for the dislocation-mediated growth of critical ω nucleus. Furthermore, analytical results demonstrate the kinetics of PT of Ti and Ti-TiB could be well unified through the Levitas’s strain-induced kinetic equation, though their accumulated plastic strain differs by a factor of ∼3. This work shed light on the role of heterogeneous phase in high-pressure deformation and PT of metals and display promising applications such as manipulation of pressure-related strength/plasticity and PT kinetics of metals via compatible second-phases.
{"title":"Heterogeneous-phase-mediated plastic deformation and phase transformation of titanium upon deviatoric stress","authors":"Bo Li , Chenhui Hu , Kaiyuan Shi , Lei Su , Yizhe Cao , Huiying Liu , Dongxu Hui , Shaodi Wang , Chuanwei Fan , Katsuyoshi Kondoh , Xin Zhang , Shengyin Zhou , Shufeng Li","doi":"10.1016/j.actamat.2026.121909","DOIUrl":"10.1016/j.actamat.2026.121909","url":null,"abstract":"<div><div>Deviatoric stress and microstructural imperfections are considered the main reasons for the promotion of phase transformation (PT) of metals at high pressure. However, structural heterogeneity induced by secondary phases will pose challenges for understanding the high-pressure deformation and PT of metallic composites. For instance, anomalies related to kinetic suppression were observed in the forward (α→ω) and reverse (ω→α) transformation of α-Ti confined by TiB upon nonhydrostatic pressure. Here, static/dynamic diamond anvil cells and synchrotron X-ray diffraction were utilized to panoramically resolve the dislocation evolution in plastic flow deformation and strain-induced PT of Ti-TiB microcomposite. Diffraction peak profile analysis reveals a decrease in dislocation density of confined α-Ti from plastic flow (1×10<sup>16</sup> m<sup>−2</sup>) to strain-induced PT (6.7×10<sup>15</sup> m<sup>−2</sup>), accompanied with the activation of ∼60% <a> slip systems and a varying combination of <c> and <c+a>. Long-range internal stress at Ti/TiB interface increases quasi-linearly to a maximum accounting for ∼17% of total pressure as the nonhydrostatic pressure increases. It probably indicates the key role of heterogeneous-stress-partition in lowering local stress required for the dislocation-mediated growth of critical ω nucleus. Furthermore, analytical results demonstrate the kinetics of PT of Ti and Ti-TiB could be well unified through the Levitas’s strain-induced kinetic equation, though their accumulated plastic strain differs by a factor of ∼3. This work shed light on the role of heterogeneous phase in high-pressure deformation and PT of metals and display promising applications such as manipulation of pressure-related strength/plasticity and PT kinetics of metals via compatible second-phases.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"306 ","pages":"Article 121909"},"PeriodicalIF":9.3,"publicationDate":"2026-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145956735","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}
Pub Date : 2026-01-10DOI: 10.1016/j.actamat.2026.121917
Zhentao Guo , Lankun Wang , Zihou Xu , Yu-Ke Zhu , Xingyan Dong , Hao Wu , Fengkai Guo , Wei Cai , Jiehe Sui , Zihang Liu
Porous bulk materials demonstrate a diverse range of functional applications, including catalysis, energy storage, and thermal management. However, the available synthesis methods are not applicable or complex for a variety of materials. In this work, we discovered that minor doping induced a compromise between plasticity and porosity in Ag2Se bulk materials, enabling the general synthesis of high-performance porous thermoelectric materials. Li/Na/Br doping reduces plasticity, increasing initial pores and suppressing plastic flow to yield grain-refined porous structures. Conversely, Cu/In/Te doping sustains/enhances plasticity, resulting in dense microstructures comparable to undoped Ag2Se. Moreover, Li doping reduces carrier concentration (nH) through cation vacancy regulation, demonstrated by density functional theory (DFT) calculations. Benefiting from the reduced electrical thermal conductivity from lowered nH and diminished lattice thermal conductivity via hierarchical phonon scattering, ultralow thermal conductivity of 0.63 W·m-1·K-1 is realized at 300 K for Ag1.95Li0.05Se. Combined with maintained high power factors, the Ag1.95Li0.05Se achieves an exceptionally high average ZT of 0.93 between 300 and 383 K. Our findings have fundamentally changed the synthesis process for thermoelectric materials, providing a new perspective on the role of doping-induced microstructural modulation and advancing the design of high-performance porous materials.
{"title":"Dopant-dependent pore formation in plastic Ag2Se contributing to ultrahigh thermoelectric performance","authors":"Zhentao Guo , Lankun Wang , Zihou Xu , Yu-Ke Zhu , Xingyan Dong , Hao Wu , Fengkai Guo , Wei Cai , Jiehe Sui , Zihang Liu","doi":"10.1016/j.actamat.2026.121917","DOIUrl":"10.1016/j.actamat.2026.121917","url":null,"abstract":"<div><div>Porous bulk materials demonstrate a diverse range of functional applications, including catalysis, energy storage, and thermal management. However, the available synthesis methods are not applicable or complex for a variety of materials. In this work, we discovered that minor doping induced a compromise between plasticity and porosity in Ag<sub>2</sub>Se bulk materials, enabling the general synthesis of high-performance porous thermoelectric materials. Li/Na/Br doping reduces plasticity, increasing initial pores and suppressing plastic flow to yield grain-refined porous structures. Conversely, Cu/In/Te doping sustains/enhances plasticity, resulting in dense microstructures comparable to undoped Ag<sub>2</sub>Se. Moreover, Li doping reduces carrier concentration (<em>n</em><sub>H</sub>) through cation vacancy regulation, demonstrated by density functional theory (DFT) calculations. Benefiting from the reduced electrical thermal conductivity from lowered <em>n</em><sub>H</sub> and diminished lattice thermal conductivity via hierarchical phonon scattering, ultralow thermal conductivity of 0.63 W·m<sup>-1</sup>·K<sup>-1</sup> is realized at 300 K for Ag<sub>1.95</sub>Li<sub>0.05</sub>Se. Combined with maintained high power factors, the Ag<sub>1.95</sub>Li<sub>0.05</sub>Se achieves an exceptionally high average <em>ZT</em> of 0.93 between 300 and 383 K. Our findings have fundamentally changed the synthesis process for thermoelectric materials, providing a new perspective on the role of doping-induced microstructural modulation and advancing the design of high-performance porous materials.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"306 ","pages":"Article 121917"},"PeriodicalIF":9.3,"publicationDate":"2026-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145974294","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}
Pub Date : 2026-01-10DOI: 10.1016/j.actamat.2026.121924
Mingzhe Liu , Xiaojia Wei , Yunsong Zhao , Yanhui Chen , Liwei Cao , Weiyi Wu , Xueqiao Li , Xingfei Pei , Ang Li , Lihua Wang , Xiaodong Han
Interfaces such as grain boundaries, phase interfaces, precipitate/matrix interfaces and defect/matrix interfaces disrupt long-range atomic arrangement order and elemental distribution continuity. Reinforcing interfaces to enhance their mechanical performance and corrosion resistance is essential for their application in harsh service environments. The interfaces of numerous alloys have been mechanically enhanced by processing or element control. In most instances, interfaces still serve as initial oxidation sites, degrading the overall properties of the alloy. Hence, improving the corrosion resistance of an interface is still necessary to improve their applicability. In particular, for Inconel 718 alloys, a primary failure scenario is corrosion-induced failure in harsh working environments, such as high-temperature coupled oxygen-rich environments. This type of failure is normally considered to be initiated from the high quantity of δ/matrix phase interfaces. However, the understanding of the oxidation mechanisms and dynamics initiated at the δ/matrix phase interface is still limited because of a lack of in situ high spatial resolution studies. Here, the thermal oxidation behavior of the semicoherent δ/matrix interface in the Inconel 718 alloy is studied via aberration-corrected environmental transmission electron microscopy (ETEM). The dynamic evolution of the two-phase interface down to the atomic scale is revealed via in situ experiments. Preferential oxidation from the δ/matrix phase interface occurs at relatively low temperatures. Moreover, selective oxidation induces mutual mass transfer on both sides of the interface. Combined with the findings from molecular dynamics simulations, the results confirm that the semicoherent δ/matrix boundary exhibits a large lattice misfit and high energy, which ultimately facilitates the preferential oxidation of the interface. This work provides direct experimental data on the stress corrosion of superalloys and offers reference data for material design and improvement.
{"title":"Oxidation-induced dissolution initiated from semicoherent δ/matrix interface in Inconel 718 superalloy","authors":"Mingzhe Liu , Xiaojia Wei , Yunsong Zhao , Yanhui Chen , Liwei Cao , Weiyi Wu , Xueqiao Li , Xingfei Pei , Ang Li , Lihua Wang , Xiaodong Han","doi":"10.1016/j.actamat.2026.121924","DOIUrl":"10.1016/j.actamat.2026.121924","url":null,"abstract":"<div><div>Interfaces such as grain boundaries, phase interfaces, precipitate/matrix interfaces and defect/matrix interfaces disrupt long-range atomic arrangement order and elemental distribution continuity. Reinforcing interfaces to enhance their mechanical performance and corrosion resistance is essential for their application in harsh service environments. The interfaces of numerous alloys have been mechanically enhanced by processing or element control. In most instances, interfaces still serve as initial oxidation sites, degrading the overall properties of the alloy. Hence, improving the corrosion resistance of an interface is still necessary to improve their applicability. In particular, for Inconel 718 alloys, a primary failure scenario is corrosion-induced failure in harsh working environments, such as high-temperature coupled oxygen-rich environments. This type of failure is normally considered to be initiated from the high quantity of δ/matrix phase interfaces. However, the understanding of the oxidation mechanisms and dynamics initiated at the δ/matrix phase interface is still limited because of a lack of <em>in situ</em> high spatial resolution studies. Here, the thermal oxidation behavior of the semicoherent δ/matrix interface in the Inconel 718 alloy is studied via aberration-corrected environmental transmission electron microscopy (ETEM). The dynamic evolution of the two-phase interface down to the atomic scale is revealed via <em>in situ</em> experiments. Preferential oxidation from the δ/matrix phase interface occurs at relatively low temperatures. Moreover, selective oxidation induces mutual mass transfer on both sides of the interface. Combined with the findings from molecular dynamics simulations, the results confirm that the semicoherent δ/matrix boundary exhibits a large lattice misfit and high energy, which ultimately facilitates the preferential oxidation of the interface. This work provides direct experimental data on the stress corrosion of superalloys and offers reference data for material design and improvement.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"306 ","pages":"Article 121924"},"PeriodicalIF":9.3,"publicationDate":"2026-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145956498","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}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号