Acta Materialia最新文献

{"title":"Integration of diamond (100) on silicon (100) via laser-assisted direct conversion of carbon","authors":"S.S. Sahoo, F. Munshe, S. Srinivasan, A. Sachan, J. Narayan","doi":"10.1016/j.actamat.2026.122933","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.122933","url":null,"abstract":"We have achieved epitaxial integration of diamond on Si(100) by depositing amorphous carbon on epitaxial YSZ buffer on Si (100),and converting this carbon layer directly into epitaxial diamond by pulsed laser annealing. The YSZ is grown epitaxially on Si (100) by domain matching epitaxy, where integral multiples of {220} planes match to accommodate >8.0% misfit between YSZ and silicon. Diamond phase is formed by nanosecond laser melting and quenching from a highly undercooled state. Diamond grows epitaxially by matching {200} planes of diamond with {220} planes of YSZ with the DME paradigm to accommodate a large misfit >30%. Epitaxial diamond crystallites are grown by using these epitaxial seeds of diamond using HFCVD. Extended HFCVD growth promotes lateral enlargement and coalescence of diamond crystallites, producing large-area diamond regions while preserving local epitaxial alignment at the diamond/YSZ interface. Raman spectroscopy was employed to characterize the bonding characteristics and phase composition of the Q-carbon and diamond. High-resolution transmission electron microscopy (HRTEM) imaging and diffraction provided direct information on diamond structure and characteristics of epitaxial growth. This approach demonstrates a viable pathway for integrating diamond with silicon platforms through laser-induced phase transformation and epitaxial growth.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"10 4 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2026-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149374441","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":"Dopant Dependent Grain Growth and Mechanical Property Heterogeneity in Al-, Cr- and Al/Cr-doped UO2 Nuclear Fuels","authors":"Pedro Foresti Jiménez, Felix Brandt, Andrey Bukaemskiy, Celina Erven, Maximilian Henkes, Philip Kegler, Daniil Shirokiy, Egor Iwaschko, Kevin D. Stuke, Christoph Hennig, Martina Klinkenberg, Gabriel L. Murphy","doi":"10.1016/j.actamat.2026.122932","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.122932","url":null,"abstract":"Al, Cr, and Al/Cr blends are added to UO₂ fuels to promote grain growth which improves fission gas retention and microstructural performance, yet despite their use as accident tolerant fuels (ATFs), their individual roles and effects on microstructure and mechanical behaviour remain poorly known. Herein, the microstructural and mechanical performance of UO<ce:inf loc=\"post\">2</ce:inf> ceramic pellets doped with Al, Cr and Al/Cr additions from 500 to 2000 molar ppm has been systematically examined. Scanning electron microscopy and electron backscatter diffraction measurements revealed significant dopant dependent microstructure and mechanical properties across the ceramic pellets: Particularly uniform grain size distributions are found for all Cr doping compositions, with a consistent increase in average grain size with progressive dopant amount. In contrast, Al- and Al/Cr-doped ceramics at higher doping concentrations (2000 and 1000-2000 molar ppm respectively), showed heterogeneous microstructures, with non-uniform grain growth and markedly smaller grains occurring at rim regions that is exacerbated with increasing Al dopant addition. This effect is discussed regarding Al exceeding its solubility in UO<ce:inf loc=\"post\">2</ce:inf>, via supporting synchrotron X-ray powder diffraction measurements, and forming potential stable Al<ce:inf loc=\"post\">2</ce:inf>O<ce:inf loc=\"post\">3</ce:inf> precipitates, or (Al,Cr)<ce:inf loc=\"post\">2</ce:inf>O<ce:inf loc=\"post\">3</ce:inf> when in the presence of Cr, which inhibit grain coarsening via Zener pinning at pellet rim regions during sintering. The difference in grain size distribution was found to further correlate with significant variations in microhardness and fracture toughness at associated rim- and centre-pellet regions. The study demonstrates how differences in dopant chemistry can affect critical ATF fuel properties which utilise Cr as a single dopant compared to Al or co-doped Al/Cr.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"501 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2026-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149374395","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":"Hierarchical toughening of Fe-Al bimetallic heterostructures through coupled intermetallic lattice chemistry, grain-boundary state and interfacial architecture","authors":"Zhijie Ding, Yinchen Wang, Jingkuan Wang, Peng Li, Jinkai Wang, Zhiwei Qin, Xiaoyang Bi, Zhuoming Tan, Hexue Wang, Xiangchen Meng, Yunwu Ma, Yongbing Li, Feifan Wang, Jianyu Li, Shiwei Xu, Honggang Dong","doi":"10.1016/j.actamat.2026.122925","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.122925","url":null,"abstract":"Robust interfaces are essential for lightweight bimetallic heterostructures in demanding load-bearing applications. However, brittle interfacial intermetallic compounds (IMCs) formed at such interfaces often exhibit limited deformability and high crack susceptibility, causing premature interfacial fracture. Herein, a Fe-Al bimetallic heterostructure with high interfacial fracture resistance is developed via hierarchical interface engineering that couples chemical-complexity regulation of interfacial IMCs, grain-boundary (GB)-state regulation, and interfacial architecture control. This strategy establishes a chemically complex interfacial reaction pathway, yielding a nanocrystalline <ce:italic>o</ce:italic>-Al<ce:inf loc=\"post\">13</ce:inf>(Co, Cr, Ni, Fe)<ce:inf loc=\"post\">4</ce:inf> IMC layer with multicomponent transition-metal (TM) sublattice occupation and Cu-enriched GBs, while simultaneously forming tortuous/interlocked interfaces. The resulting heterostructure achieves an average fracture strength of 263.2 MPa, representing an approximately 110.2% increase in fracture strength relative to reported heterostructures with comparable IMC-layer thickness, while the current interfacial IMC exhibits an indentation-derived toughness of 28.2 MPa·m<ce:sup loc=\"post\">1/2</ce:sup>. Importantly, these improvements are achieved without relying on conventional IMC-layer thinning. The enhanced fracture resistance originates from hierarchically coupled interfacial toughening mechanisms. Metal-sublattice electronic heterogeneity enhances intrinsic IMC fracture tolerance by enabling strain-responsive redistribution of TM d states and diversification of the metallic-bond network, while Cu enrichment at GBs facilitates GB-mediated deformation accommodation within the nanocrystalline IMC. Coupled with load transfer through tortuous and interlocked interfaces, these effects establish a cooperative toughening framework beyond the conventional thickness-dominated view of fracture resistance and provide a design principle for IMC-governed dissimilar-metal interfaces.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"17 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2026-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149374443","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structural origin of high piezoelectricity, electrostrain and energy density in quantum paraelectric doped Na0.5Bi0.5TiO3 piezoelectric","authors":"Gobinda Das Adhikary, Swadesh Laha, Deepak Sharma, Gudeta Jafo Muleta, Anatoliy Senyshyn, Rajeev Ranjan","doi":"10.1016/j.actamat.2026.122918","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.122918","url":null,"abstract":"Among Na<ce:inf loc=\"post\">0.5</ce:inf>Bi<ce:inf loc=\"post\">0.5</ce:inf>TiO<ce:inf loc=\"post\">3</ce:inf>-based lead-free piezoelectrics, the quantum paraelectric (SrTiO<ce:inf loc=\"post\">3</ce:inf>) doped flexible Na<ce:inf loc=\"post\">0.5</ce:inf>Bi<ce:inf loc=\"post\">0.5</ce:inf>TiO<ce:inf loc=\"post\">3</ce:inf> system is well known in terms of multi-functionality. However, the structural mechanisms responsible for these functionalities remain ambiguous. Here, we present a comprehensive investigation of (1−x)Na<ce:inf loc=\"post\">0.5</ce:inf>Bi<ce:inf loc=\"post\">0.5</ce:inf>TiO<ce:inf loc=\"post\">3</ce:inf>–(x)SrTiO<ce:inf loc=\"post\">3</ce:inf> (NBT–ST) (0 ≤ x ≤ 0.50) using temperature-dependent x-ray and neutron powder diffraction, room temperature electron diffraction in conjunction with dielectric, ferroelectric, pyroelectric, and piezoelectric measurements. We uncover a sequence of composition- and temperature-driven structural instabilities associated with competing polar (<ce:italic>R</ce:italic>3<ce:italic>c</ce:italic>) and nonpolar (<ce:italic>P</ce:italic>4<ce:italic>bm</ce:italic>) phases, which govern the evolution of polarization dynamics and electromechanical response. These instabilities produce pronounced anomalies in dielectric permittivity, depolarization behavior, piezoelectric coefficient, recoverable energy density, and electric-field-induced strain. Based on these findings, we establish a unified composition–temperature (x)–(T) phase diagram that reconciles previously conflicting interpretations of the phase evolution and functional properties of the NBT–ST system. The present work provides a coherent structural framework linking phase instability to enhanced multifunctional performance and offers general design principles for the development of high-performance lead-free piezoelectric materials.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"21 1","pages":"122918"},"PeriodicalIF":9.4,"publicationDate":"2026-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149358768","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":"Achieving High Yield Strength and High Strain-hardening Rate by Co-precipitation of HCP and σ Phases in a Medium-Entropy Alloy","authors":"Zhong Li, Taiwu Yu, Yang Li, Yifang Liu, Zhenhua Zhang, Shan Zhang, Xiaolian Liu, Xingyu Liu, Hanpu Liang, Shiddhartha Ramprakash, Pengfei Guan, Xuefeng Zhang","doi":"10.1016/j.actamat.2026.122915","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.122915","url":null,"abstract":"Achieving high yield strength and high strain-hardening rate while retaining a favorable strength–ductility balance remains a major challenge in precipitation-strengthened medium-entropy alloys (MEAs). Here, we propose a strengthening and strain-hardening strategy based on the co-precipitation of soft and hard phases in a CoNiV-based MEA. By the co-addition of Al and Mo, a dual-precipitate architecture consisting of V-rich soft HCP precipitates and Mo-rich hard σ precipitates is successfully constructed in the (CoNiV)<ce:inf loc=\"post\">96</ce:inf>Al<ce:inf loc=\"post\">2</ce:inf>Mo<ce:inf loc=\"post\">2</ce:inf> (VAM2.0) alloy. Microstructural characterizations reveal that the soft high entropy HCP precipitates deform cooperatively with the FCC matrix and effectively alleviate local stress concentrations, whereas the hard σ precipitates strongly impede dislocation motion and promote the formation of gradient dislocation structures. The synergistic interactions among dual precipitates, coherent interfaces, and heterogeneous dislocation structures lead to effective stress accommodation, precipitation strengthening, and sustained strain hardening. Consequently, the VAM2.0 alloy achieves a yield strength of 1429 MPa, an ultimate tensile strength of 1817 MPa, a fracture elongation of 12.4%, and a high strain-hardening rate exceeding 4 GPa over most of the strain-hardening stage. This work demonstrates a previously unexplored soft–hard co-precipitation mechanism, in which deformable HCP precipitates and strengthening σ precipitates cooperate to achieve high yield strength and high strain-hardening rate while maintaining a strength–ductility balance, providing a new strategy for designing high-performance medium- and high-entropy alloys.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"503 1","pages":"122915"},"PeriodicalIF":9.4,"publicationDate":"2026-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149358769","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":"3D Observations of Grain Growth in Textured and Untextured Undoped Alumina","authors":"Hailey E. Hall, Joel B. Harley, Michael R. Tonks, Michael S. Kesler, Amanda R. Krause","doi":"10.1016/j.actamat.2026.122922","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.122922","url":null,"abstract":"The impact of grain boundary (GB) character on grain growth is assessed by studying microstructural evolution in both textured and untextured undoped alumina. Laboratory diffraction contrast tomography (LabDCT) is used to track individual grains in both microstructures across multiple heat treatment timesteps. Using this 3D data, GB character, grain morphology, GB velocity, and GB reduced mobility are measured and compared between samples slip cast inside and outside of a strong magnetic field (9T). Samples slip cast outside of the magnetic field exhibit random orientations whereas the samples slip cast in the magnetic field exhibit both crystallographic texture and a preferred GB character with a preference for the [0001] misorientation axis and (0001) plane inclination. GBs in untextured, undoped alumina migrated at a faster rate than textured, undoped alumina despite the higher average curvature found in the textured case. Furthermore, we find that low energy GBs (e.g. basal boundaries) tend to migrate at rates exceeding those of higher energy boundaries in textured alumina. Finally, we observe that both textured and untextured alumina grains adopt a slightly elongated grain morphology. The aspect ratios of untextured (1.88) and textured (2.13) alumina are relatively similar despite the high population of high mobility GBs in textured alumina. We postulate that differences in microstructural evolution between untextured and textured alumina arise due to changes in the GB network.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"15 1","pages":"122922"},"PeriodicalIF":9.4,"publicationDate":"2026-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149358766","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":"Insight into the two competing migration mechanisms of Σ5(120) grain boundary in face-centered cubic nickel","authors":"Guoshuai Yao, Hongxian Xie, Guang-Hong Lu","doi":"10.1016/j.actamat.2026.122921","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.122921","url":null,"abstract":"The migration mechanisms of Σ5(120) grain boundary (GB) in nickel under free and fixed boundary conditions were investigated by molecular dynamics simulations. Under the free boundary condition, the GB migrates via shear-coupled mechanism, while under fixed boundary condition, the GB migrates initially via the shear-coupled mechanism, then switched to a pure shuffling mechanism. The GB migration is mediated by the nucleation, motion, and mutual annihilation of two types of disconnections, and the characteristics of these disconnections were determined. Finally, the GB migration energy barrier​ for the shear-coupled​ and pure shuffling mechanisms was calculated, the latter is approximately 4.3 times as high as the former, which is the underlying reason why the shear-coupled mechanism is more readily activated than the pure shuffling mechanism, and the pure shuffle mechanism only becomes active once the shear-coupled mechanism is suppressed. The present study contributes to a deeper understanding of GB migration behavior under different constraint conditions.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"64 1","pages":"122921"},"PeriodicalIF":9.4,"publicationDate":"2026-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149358767","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":"Pencil glide, crystal rotation, and non-Schmid slip behavior in MoReW single crystals during tensile deformation","authors":"Oleg N. Senkov, Robert Wheeler, Michael A. Velez","doi":"10.1016/j.actamat.2026.122923","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.122923","url":null,"abstract":"This study investigates the tensile deformation behavior of a single-phase BCC MoReW refractory alloy using in-situ micro-tensile testing of single-crystalline and bi-crystalline specimens inside a scanning electron microscope, together with macroscopic tensile testing of polycrystalline specimens. While polycrystalline and bi-crystalline specimens exhibit premature intergranular fracture with no or very little macroscopic plastic deformation, preventing their plastic deformation behavior from being assessed, single-crystalline specimens demonstrate high strength (yield strength up to ∼1 GPa) and significant tensile ductility (7–36%), strongly dependent on crystallographic orientation. Slip trace analysis and crystallographic characterization reveal that plastic deformation occurs primarily by &lt;111&gt; pencil glide on {112}, {123}, {134} and occasionally {235} planes, consistent with established BCC deformation behavior but exhibiting pronounced slip-plane selectivity. {110}&lt;111&gt; slip systems show minimal activity despite favorable Schmid factors, indicating estimated lower bound of ∼452 MPa for their critical resolved shear stress (CRSS). The CRSS values for other active slip systems are found to be approximately orientation-independent (∼424–438 MPa), despite pronounced anisotropy in macroscopic strength and ductility. Significant crystal rotation is observed during deformation, particularly in regions of strain localization and necking, with tensile axes rotating toward active slip directions along crystallographically defined paths. In some orientations, a secondary slip direction becomes active at higher strains, influencing strain localization and deformation stability. The results demonstrate substantial intrinsic tensile plasticity of single-crystalline MoReW, governed by dislocation glide rather than twinning, in contrast to prior compression studies and consistent with pronounced tensile-compression asymmetry and non-Schmid slip-plane selection. This intrinsic plasticity of MoReW is masked in polycrystalline material by premature intergranular fracture.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"10 1","pages":"122923"},"PeriodicalIF":9.4,"publicationDate":"2026-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149358765","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":"Phase Modulation Coupling Defect Engineering Strategy Enables Reliable BSPT System for HT Piezoelectric Accelerometer","authors":"Xuanyu Chen, Wenlong Xu, Jun Zhao, Mupeng Zheng, Yudong Hou","doi":"10.1016/j.actamat.2026.122917","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.122917","url":null,"abstract":"The rapid development of the aerospace and nuclear energy fields urgently requires high-temperature piezoelectric accelerometers (HTPAs) to achieve intelligent sensing of the working state of vibrating machines in extreme environments. The BiScO<ce:inf loc=\"post\">3</ce:inf>-PbTiO<ce:inf loc=\"post\">3</ce:inf> (BSPT) system has attracted attention due to its simultaneous high Curie temperature (<ce:italic>T</ce:italic><ce:inf loc=\"post\">C</ce:inf>) and high piezoelectric performance. However, applying it to HTPAs operating at temperatures above 400 °C is still necessary to obtain both high insulation resistivity and robust thermal stability. Here, guided by the phase modulation coupling defect engineering strategy, these problems have been addressed in CuO modified BSPT system. The selected CuO dopants can achieve multiple functions: they not only help reduce the sintering temperature of the BSPT system to 950 °C, but also drive the phase composition to move to the morphotropic phase boundary (MPB) region, thereby increasing the piezoelectric coefficient. And the neutral defects can significantly enhance the insulation resistivity and stabilize the piezoelectric performance within a wide temperature range. A comprehensively balanced performance was achieved in the optimal CuO modified specimen with <ce:italic>d</ce:italic><ce:inf loc=\"post\">33</ce:inf>=365 pC/N and <ce:italic>ρ</ce:italic><ce:inf loc=\"post\">400°C</ce:inf>&gt;10<ce:sup loc=\"post\">7</ce:sup> Ω·cm, which also give a high depolarization temperature (<ce:italic>T</ce:italic><ce:inf loc=\"post\">d</ce:inf>) of 435 °C. The <ce:italic>x</ce:italic>=0.5 HTPA exhibits a high charge sensitivity of 95.3 pC/g. It sustains stable sensing performance across a broad temperature range of 25-420°C and maintains nearly invariant sensitivity even after 3×10<ce:sup loc=\"post\">6</ce:sup> continuous vibration cycles, demonstrating highly reliable thermal stability and fatigue endurance. This work provides a vital material foundation and technical paradigm for the development of next-generation HTPAs.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"257 1","pages":"122917"},"PeriodicalIF":9.4,"publicationDate":"2026-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149358924","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":"Critical role of austenite in yielding behavior of ultrahigh-strength maraging steels fabricated via laser powder bed fusion","authors":"Shidong Wang, Jiang Ju, Pengyu Wen, Wu Gong, Takuro Kawasaki, Stefanus Harjo, Youyou Zhang, Siyuan Wei, Baode Sun, Hao Chen","doi":"10.1016/j.actamat.2026.122914","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.122914","url":null,"abstract":"High fractions of soft austenite are generally considered incompatible with the retention of ultrahigh yield strength (YS) in maraging steels. However, laser powder bed fusion (L-PBF) maraging steels subjected to direct aging typically exhibit ultrahigh YS (∼2 GPa) together with a high fraction (10-20 %) of cellular reverted austenite, and the underlying mechanisms remain poorly understood. In this work, we demonstrate that, regarding cellular austenite reversion, molybdenum (Mo) segregation along cell walls, inherited from the L-PBF process, lowers the local martensite start (<ce:italic>M<ce:inf loc=\"post\">s</ce:inf></ce:italic>) temperature, thereby preserving a relatively high density of retained austenite even after cryogenic treatment. This abundant retained austenite serves as pre-existing nuclei for austenite reversion during aging, thus accelerating the reversion kinetics and giving rise to a high fraction of cellular reverted austenite. Regarding yielding behaviors, the cellular austenite, which is devoid of nanoprecipitates and mechanically stable enough to avoid stress-induced martensitic transformation, yields before the martensitic matrix. Nevertheless, the ability of cellular austenite to govern macroscopic yielding mainly depends on its content and size. At a lower content (around 20 %) and smaller size, its plastic strain contribution remains limited, so that macroscopic yielding is not triggered even under an applied stress exceeding 2 GPa. Conversely, at a relatively high content (about 35 %) and larger size, the accumulated strain can trigger macroscopic yielding even before the yielding of the martensitic matrix. These insights may guide the design of dual-phase microstructures and the optimization of mechanical properties in L-PBF maraging steels.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"259 1","pages":"122914"},"PeriodicalIF":9.4,"publicationDate":"2026-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149358796","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}