Fine-grained microstructures are essential for achieving high strength in metallic polycrystals, and oxide dispersion is an effective strategy to suppress grain coarsening. However, during sintering, oxide-induced grain boundary (GB) pinning is often accompanied by sluggish densification, as both processes are thermally activated. Herein, we establish a correlation between the intrinsic growth behavior of second-phase oxides (Al, Ce, La, Zr) and the sintering kinetics of oxide-dispersion-strengthened W (ODS-W) alloys through experiments and first-principles calculations. A nearly linear relationship is revealed between the apparent sintering activation energy and oxide growth mobility. In contrast to the conventional view that second-phase particles inhibit diffusion and densification, as observed in W-La2O3 and W-CeO2 alloys, Al- or Zr-oxide-strengthened W alloys display a strikingly opposite effect, promoting sintering and achieving high relative densities (∼ 95 %) at a low temperature of ∼ 1500°C. Zr and Al species preferentially exist as atomically dispersed or small-cluster states, which reduce W vacancy formation energies and diffusion barriers, thereby facilitating rapid atomic transport along W GBs during sintering. Accelerated densification leads to ultrafine-grained microstructures (∼300 nm), where the combined effects of grain refinement and oxide dispersion strengthening (ODS) deliver high hardness (740.7 HV) and compressive yield strength (2288.86 MPa), positioning them among the best-performing W alloys reported to date.
{"title":"Oxide-induced fast densification in W alloys","authors":"Fengsong Fan, Sijia Liu, Jie Wang, Haifeng Xu, Huihuang Song, Qiang Chen, Haoyang Wu, Deyin Zhang, Baorui Jia, Xuanhui Qu, Mingli Qin","doi":"10.1016/j.actamat.2026.122146","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.122146","url":null,"abstract":"Fine-grained microstructures are essential for achieving high strength in metallic polycrystals, and oxide dispersion is an effective strategy to suppress grain coarsening. However, during sintering, oxide-induced grain boundary (GB) pinning is often accompanied by sluggish densification, as both processes are thermally activated. Herein, we establish a correlation between the intrinsic growth behavior of second-phase oxides (Al, Ce, La, Zr) and the sintering kinetics of oxide-dispersion-strengthened W (ODS-W) alloys through experiments and first-principles calculations. A nearly linear relationship is revealed between the apparent sintering activation energy and oxide growth mobility. In contrast to the conventional view that second-phase particles inhibit diffusion and densification, as observed in W-La<sub>2</sub>O<sub>3</sub> and W-CeO<sub>2</sub> alloys, Al- or Zr-oxide-strengthened W alloys display a strikingly opposite effect, promoting sintering and achieving high relative densities (∼ 95 %) at a low temperature of ∼ 1500°C. Zr and Al species preferentially exist as atomically dispersed or small-cluster states, which reduce W vacancy formation energies and diffusion barriers, thereby facilitating rapid atomic transport along W GBs during sintering. Accelerated densification leads to ultrafine-grained microstructures (∼300 nm), where the combined effects of grain refinement and oxide dispersion strengthening (ODS) deliver high hardness (740.7 HV) and compressive yield strength (2288.86 MPa), positioning them among the best-performing W alloys reported to date.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"85 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2026-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147489790","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 : 2026-03-20DOI: 10.1016/j.actamat.2026.122147
Amit Kumar Singh, Priyanka Agrawal, Eric Kusterer, Fredrick N. Michael, Rajiv S. Mishra
Tungsten-based alloys exhibit poor printability during laser beam powder bed fusion (PBF-LB) due to their high crack susceptibility index (CSI) and intrinsic brittleness associated with a high ductile-to-brittle transition temperature, leading to severe solidification cracking in additively manufactured components. Addressing this challenge requires alloy design strategies that reduce crack susceptibility while maintaining the high-temperature capability of tungsten alloys. In this study, two ternary alloys, W–10Nb–xC (x = 0.45 and 1.0 wt.%), were designed using an integrated computational materials engineering (ICME) framework to investigate the role of interstitial carbon in mitigating cracking during PBF-LB processing. The crack susceptibility index was evaluated using CALPHAD-based thermodynamic calculations coupled with heat-transfer and material-flow simulations representative of PBF-LB conditions. A modified back-diffusion treatment was incorporated to account for solute redistribution under the high cooling rates associated with variations in laser scanning speed. Increasing carbon content promotes a higher volume fraction of carbide phases, which is typically expected to increase brittleness and cracking susceptibility. However, CALPHAD-based CSI calculations predict that the lower eutectic alloy (0.45 wt.% C) exhibits higher cracking susceptibility than the 1.0 wt.% C alloy, consistent with experimental observations. The improved printability of the higher-carbon alloy arises from the formation of coarser eutectic structures that enhance liquid backfilling and accommodate tensile strains during solidification. Although both alloys exhibit compressive strengths of ∼1200 MPa at room temperature, the higher fraction of WC and NbC carbides in the 1.0 wt.% C alloy reduces strain relative to 0.45 wt.% C alloy.
{"title":"Crack susceptibility of novel W-Nb-C alloy for laser beam powder bed fusion additive manufacturing","authors":"Amit Kumar Singh, Priyanka Agrawal, Eric Kusterer, Fredrick N. Michael, Rajiv S. Mishra","doi":"10.1016/j.actamat.2026.122147","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.122147","url":null,"abstract":"Tungsten-based alloys exhibit poor printability during laser beam powder bed fusion (PBF-LB) due to their high crack susceptibility index (CSI) and intrinsic brittleness associated with a high ductile-to-brittle transition temperature, leading to severe solidification cracking in additively manufactured components. Addressing this challenge requires alloy design strategies that reduce crack susceptibility while maintaining the high-temperature capability of tungsten alloys. In this study, two ternary alloys, W–10Nb–xC (x = 0.45 and 1.0 wt.%), were designed using an integrated computational materials engineering (ICME) framework to investigate the role of interstitial carbon in mitigating cracking during PBF-LB processing. The crack susceptibility index was evaluated using CALPHAD-based thermodynamic calculations coupled with heat-transfer and material-flow simulations representative of PBF-LB conditions. A modified back-diffusion treatment was incorporated to account for solute redistribution under the high cooling rates associated with variations in laser scanning speed. Increasing carbon content promotes a higher volume fraction of carbide phases, which is typically expected to increase brittleness and cracking susceptibility. However, CALPHAD-based CSI calculations predict that the lower eutectic alloy (0.45 wt.% C) exhibits higher cracking susceptibility than the 1.0 wt.% C alloy, consistent with experimental observations. The improved printability of the higher-carbon alloy arises from the formation of coarser eutectic structures that enhance liquid backfilling and accommodate tensile strains during solidification. Although both alloys exhibit compressive strengths of ∼1200 MPa at room temperature, the higher fraction of WC and NbC carbides in the 1.0 wt.% C alloy reduces strain relative to 0.45 wt.% C alloy.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"13 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2026-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147492737","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 : 2026-03-19DOI: 10.1016/j.actamat.2026.122143
Zhengniu Pan, Sijing Zhu, Yi Wang, Zhen Fan, Jisheng Liang, Shiyuan Zhao, Jun-Liang Chen, Zhongwei Zhang, Zhixiang Zhang, Qi Zhou, Jie Gao, Huaizhou Zhao, Lei Miao
The n-type Mg3+δ(Sb,Bi)2‐based system has recently emerged as a breakthrough class of thermoelectric (TE) materials, drawing considerable interest for its eco‐friendly composition and potential to replace conventional commercial counterparts. However, the precise regulation of grain boundaries in Mg-based materials—akin to wielding an accurate scalpel—so as to extremely optimize thermoelectric performance and device properties remains ill-defined. In this study, the incorporation of Ga into the Mg3(Sb,Bi)2 matrix via high‐energy ball milling (HBM) and spark plasma sintering (SPS) yielded an ultralow lattice thermal conductivity of 0.41 W m-1 K-1 at 300 K, a superior figure of merit (ZT) exceeding 1.84 at 673 K, and a high average ZT (ZTavg) of 1.55 across 300—773 K. The lattice thermal conductivity of Ga‐modified Mg3+δ(Sb,Bi)2 is markedly reduced over the entire temperature range, primarily due to the enhanced Kapitza thermal resistivity (ρKapitza) resulting from the introduction of a liquid‐like phase at grain boundaries (GBs), which strengthens phonon scattering. while, Ohmic-like metal–semiconductor junctions form at the interfaces between the Ga/Bi secondary phases and the Mg3+δ(Sb,Bi)2 matrix lead to superior power factor. The high performance of Ga‐Mg3+δ(Sb,Bi)2 enabled a two‐pair module based on Mg3.2Ga0.04Sb1.5Bi0.49Te0.01/ MgAgSb to achieve a conversion efficiency (η) of ∼6.0% at ΔT = 300 K. As a result, this work demonstrates significant theoretical and practical value in areas such as thermal management and thermoelectric material design.
{"title":"Synergistic Optimization of Electrical and Thermal Transport in Mg3+δ(Sb, Bi)2 through Ga-Modified Grain Boundaries","authors":"Zhengniu Pan, Sijing Zhu, Yi Wang, Zhen Fan, Jisheng Liang, Shiyuan Zhao, Jun-Liang Chen, Zhongwei Zhang, Zhixiang Zhang, Qi Zhou, Jie Gao, Huaizhou Zhao, Lei Miao","doi":"10.1016/j.actamat.2026.122143","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.122143","url":null,"abstract":"The n-type Mg<sub>3+δ</sub>(Sb,Bi)<sub>2</sub>‐based system has recently emerged as a breakthrough class of thermoelectric (TE) materials, drawing considerable interest for its eco‐friendly composition and potential to replace conventional commercial counterparts. However, the precise regulation of grain boundaries in Mg-based materials—akin to wielding an accurate scalpel—so as to extremely optimize thermoelectric performance and device properties remains ill-defined. In this study, the incorporation of Ga into the Mg<sub>3</sub>(Sb,Bi)<sub>2</sub> matrix via high‐energy ball milling (HBM) and spark plasma sintering (SPS) yielded an ultralow lattice thermal conductivity of 0.41 W m<sup>-1</sup> K<sup>-1</sup> at 300 K, a superior figure of merit (<em>ZT</em>) exceeding 1.84 at 673 K, and a high average <em>ZT</em> (<em>ZT<sub>avg</sub></em>) of 1.55 across 300—773 K. The lattice thermal conductivity of Ga‐modified Mg<sub>3+δ</sub>(Sb,Bi)<sub>2</sub> is markedly reduced over the entire temperature range, primarily due to the enhanced Kapitza thermal resistivity (ρ<sub>Kapitza</sub>) resulting from the introduction of a liquid‐like phase at grain boundaries (GBs), which strengthens phonon scattering. while, Ohmic-like metal–semiconductor junctions form at the interfaces between the Ga/Bi secondary phases and the Mg<sub>3+δ</sub>(Sb,Bi)<sub>2</sub> matrix lead to superior power factor. The high performance of Ga‐Mg<sub>3+δ</sub>(Sb,Bi)<sub>2</sub> enabled a two‐pair module based on Mg<sub>3.2</sub>Ga<sub>0.04</sub>Sb<sub>1.5</sub>Bi<sub>0.49</sub>Te<sub>0.01</sub>/ MgAgSb to achieve a conversion efficiency (<em>η</em>) of ∼6.0% at ΔT = 300 K. As a result, this work demonstrates significant theoretical and practical value in areas such as thermal management and thermoelectric material design.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"44 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2026-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147489338","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}
The fracture of WC-Co cemented carbides is a multiscale process involving interactions from atomic to macroscopic levels. This study develops a hierarchical multiscale framework combining molecular dynamics (MD) and finite element (FE) methods to analyze crack propagation in these composites. Nanoscale MD simulations characterized the traction-separation responses for four critical fracture paths: WC/Co interface, WC/WC interface, WC transgranular, and Co phase fracture. These curves were fitted to a bilinear cohesive zone model to parameterize FE cohesive elements. Two FE model types were constructed: single-interface and composite-interface compact tension specimens, the latter using Voronoi tessellation to represent realistic microstructures. The composite model successfully predicted the fracture toughness of seven WC-Co variants with varying grain sizes. Predicted values closely matched experimental measurements, with a maximum error below 7.9%. This work validates the effectiveness of a cohesive zone model-based multiscale approach in bridging nanoscale mechanisms and macroscopic fracture behavior in heterogeneous materials.
{"title":"A Multiscale Investigation of Crack Propagation in WC-Co Cemented Carbides: From Atomistic Mechanisms to Macroscopic Fracture Behavior","authors":"Lirong Huang, Kaichen Luo, Kai Ming, Yuhang Chen, Zeqian Shi, Jian Yang, Xiao Qin","doi":"10.1016/j.actamat.2026.122144","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.122144","url":null,"abstract":"The fracture of WC-Co cemented carbides is a multiscale process involving interactions from atomic to macroscopic levels. This study develops a hierarchical multiscale framework combining molecular dynamics (MD) and finite element (FE) methods to analyze crack propagation in these composites. Nanoscale MD simulations characterized the traction-separation responses for four critical fracture paths: WC/Co interface, WC/WC interface, WC transgranular, and Co phase fracture. These curves were fitted to a bilinear cohesive zone model to parameterize FE cohesive elements. Two FE model types were constructed: single-interface and composite-interface compact tension specimens, the latter using Voronoi tessellation to represent realistic microstructures. The composite model successfully predicted the fracture toughness of seven WC-Co variants with varying grain sizes. Predicted values closely matched experimental measurements, with a maximum error below 7.9%. This work validates the effectiveness of a cohesive zone model-based multiscale approach in bridging nanoscale mechanisms and macroscopic fracture behavior in heterogeneous materials.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"419 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2026-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147489791","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}
The formation of oxygen vacancies in oxide films can dramatically alter their inherent properties, especially in ultrathin films down to monolayer limit. Gaining an effective control of oxygen content in low-dimensional oxides is essential for their nanoelectronic applications. Herein, we demonstrate enhanced ferromagnetism in atomically designed LaMnO3/SrTiO3 (LMO/STO) heterostructures, where the surface oxygen content is controlled by the termination conversion utilizing an SrRuO3 (SRO) buffer layer. X-ray absorption spectroscopy reveals increased Mn oxidation states along with enhanced hybridization between Mn-3d and O-2p states as the termination of LMO converts from MnO2 to LaO atomic plane. Spatially-resolved electron energy loss spectroscopy further clarifies that the oxidation states of outermost Mn ions recover their bulk level after termination switch, although the electron accumulation at the bottom interface with STO remains virtually unaltered. These results are in line with previous first-principles studies where the disappeared ferromagnetism in ultrathin LMO is ascribed to the oxygen vacancies formed at the MnO2 open surface. Moreover, for LMO films thinner than four unit cells, capping with another SRO monolayer is found to be crucial to restore the oxygen stoichiometry required for a ferromagnetic ground state. Our findings suggest a general strategy to engineer the oxygen stoichiometry in (quasi) two-dimensional oxide materials for developing high-performance nanoelectronic devices.
{"title":"Surface oxygen control retains low-dimensional ferromagnetic insulator in atomically designed oxide heterostructures","authors":"Xiang Xu, Haonan Wang, Zijian Chen, Jie Tu, Xiaoyu Qiu, Yujie Zhou, Chen Zhou, Zhao Guan, Wenyi Tong, Zhenzhong Yang, Ni Zhong, Pinghua Xiang, Chungang Duan, Binbin Chen","doi":"10.1016/j.actamat.2026.122142","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.122142","url":null,"abstract":"The formation of oxygen vacancies in oxide films can dramatically alter their inherent properties, especially in ultrathin films down to monolayer limit. Gaining an effective control of oxygen content in low-dimensional oxides is essential for their nanoelectronic applications. Herein, we demonstrate enhanced ferromagnetism in atomically designed LaMnO<sub>3</sub>/SrTiO<sub>3</sub> (LMO/STO) heterostructures, where the surface oxygen content is controlled by the termination conversion utilizing an SrRuO<sub>3</sub> (SRO) buffer layer. X-ray absorption spectroscopy reveals increased Mn oxidation states along with enhanced hybridization between Mn-3<em>d</em> and O-2<em>p</em> states as the termination of LMO converts from MnO<sub>2</sub> to LaO atomic plane. Spatially-resolved electron energy loss spectroscopy further clarifies that the oxidation states of outermost Mn ions recover their bulk level after termination switch, although the electron accumulation at the bottom interface with STO remains virtually unaltered. These results are in line with previous first-principles studies where the disappeared ferromagnetism in ultrathin LMO is ascribed to the oxygen vacancies formed at the MnO<sub>2</sub> open surface. Moreover, for LMO films thinner than four unit cells, capping with another SRO monolayer is found to be crucial to restore the oxygen stoichiometry required for a ferromagnetic ground state. Our findings suggest a general strategy to engineer the oxygen stoichiometry in (quasi) two-dimensional oxide materials for developing high-performance nanoelectronic devices.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"12 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2026-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147478203","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 : 2026-03-17DOI: 10.1016/j.actamat.2026.122136
Camila A. Teixeira, Ujjval Bansal, Guillaume Laplanche, Peter Gumbsch, Subin Lee, Christoph Kirchlechner
Deformation twinning is an important deformation mechanism for low stacking fault energy face-centered cubic (FCC) alloys including multi-principal element alloys, however, its underlying mechanism remains incompletely understood. In this work, we applied in situ scanning electron microscope (SEM) micro-pillar compression combined with microstructural investigations to gain insights into the fundamental mechanism of deformation twinning and its stress and/or strain dependence. Our findings reveal that the morphology of the deformation twins and the controlling mechanism vary with micro-pillar size. In sub-micron pillars, single-slip based twinning models like the three-layer model were predominant as confirmed by in situ deformation and post-mortem microstructural analyses. For pillar diameters above 3 µm, two different twin variants were observed including one formed by the three-layer mechanism, although the secondary twinning mechanism remains unclear. When the pillar diameter increased to 10 µm, the applied stresses was insufficient to activate deformation twinning, and dislocation slip became the dominant deformation mode. A quantitative stress analysis of pillars ranging from 0.14 µm to 10 µm in diameter showed a lower bound for twinning stress of approximately 130 MPa. Finally, size dependence investigations revealed no significant difference between twinning stress and full dislocation slip critical resolved shear stress. This not only proves that dislocation slip is a prerequisite for twinning, but also indicates that, above a threshold stress, twinning could be more strain rather than stress-dependent.
{"title":"Mechanistic insights and activation stress analysis of deformation twinning in the Cantor multi-principal element alloy","authors":"Camila A. Teixeira, Ujjval Bansal, Guillaume Laplanche, Peter Gumbsch, Subin Lee, Christoph Kirchlechner","doi":"10.1016/j.actamat.2026.122136","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.122136","url":null,"abstract":"Deformation twinning is an important deformation mechanism for low stacking fault energy face-centered cubic (FCC) alloys including multi-principal element alloys, however, its underlying mechanism remains incompletely understood. In this work, we applied <em>in situ</em> scanning electron microscope (SEM) micro-pillar compression combined with microstructural investigations to gain insights into the fundamental mechanism of deformation twinning and its stress and/or strain dependence. Our findings reveal that the morphology of the deformation twins and the controlling mechanism vary with micro-pillar size. In sub-micron pillars, single-slip based twinning models like the three-layer model were predominant as confirmed by <em>in situ</em> deformation and <em>post-mortem</em> microstructural analyses. For pillar diameters above 3 µm, two different twin variants were observed including one formed by the three-layer mechanism, although the secondary twinning mechanism remains unclear. When the pillar diameter increased to 10 µm, the applied stresses was insufficient to activate deformation twinning, and dislocation slip became the dominant deformation mode. A quantitative stress analysis of pillars ranging from 0.14 µm to 10 µm in diameter showed a lower bound for twinning stress of approximately 130 MPa. Finally, size dependence investigations revealed no significant difference between twinning stress and full dislocation slip critical resolved shear stress. This not only proves that dislocation slip is a prerequisite for twinning, but also indicates that, above a threshold stress, twinning could be more strain rather than stress-dependent.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"6 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2026-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147471133","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}
Understanding the evolution of dislocation structures during plastic deformation is critical for predicting the mechanical performance of metallic materials. In this work, we applied in situ scanning electron microscopy/electron backscatter diffraction tensile testing combined with multifractal (MF) analysis to assess deformation-induced dislocation structure evolution in solution-annealed 304L stainless steel, both in its as-received and neutron-irradiated states (5.4 displacements per atom). The analysis of kernel average misorientation patterns revealed the formation of hierarchical dislocation arrangements that exhibit clear MF scaling behavior. Despite pronounced visual differences between nonirradiated and irradiated specimens—most notably, the appearance of dislocation channels after irradiation—the singularity spectra suggest that both conditions give rise to similar underlying hierarchical structures. MF analysis provides a quantitative measure of the spatial complexity and self-organization of dislocation patterns, highlighting the accelerated emergence and evolution of the dislocation structures in irradiated polycrystalline materials, as well as the limitation of their spatial extent. The findings indicate that irradiation not only modifies microstructure but also alters correlation-driven dislocation organization. More generally, they demonstrate that MF analysis is a powerful tool for probing mesoscale deformation mechanisms.
{"title":"Emerging hierarchical dislocation structures: Insights from scanning electron microscopy-electron backscatter diffraction in situ tensile testing and multifractal analysis","authors":"Mikhail Lebyodkin, Maxim Gussev, Jamieson Brechtl, Tatiana Lebedkina","doi":"10.1016/j.actamat.2026.122138","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.122138","url":null,"abstract":"Understanding the evolution of dislocation structures during plastic deformation is critical for predicting the mechanical performance of metallic materials. In this work, we applied in situ scanning electron microscopy/electron backscatter diffraction tensile testing combined with multifractal (MF) analysis to assess deformation-induced dislocation structure evolution in solution-annealed 304L stainless steel, both in its as-received and neutron-irradiated states (5.4 displacements per atom). The analysis of kernel average misorientation patterns revealed the formation of hierarchical dislocation arrangements that exhibit clear MF scaling behavior. Despite pronounced visual differences between nonirradiated and irradiated specimens—most notably, the appearance of dislocation channels after irradiation—the singularity spectra suggest that both conditions give rise to similar underlying hierarchical structures. MF analysis provides a quantitative measure of the spatial complexity and self-organization of dislocation patterns, highlighting the accelerated emergence and evolution of the dislocation structures in irradiated polycrystalline materials, as well as the limitation of their spatial extent. The findings indicate that irradiation not only modifies microstructure but also alters correlation-driven dislocation organization. More generally, they demonstrate that MF analysis is a powerful tool for probing mesoscale deformation mechanisms.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"15 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2026-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147465557","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}
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