Acta Materialia最新文献

{"title":"Substitutional solute grain boundary segregation enhances resistance to hydrogen embrittlement in compositionally complex alloys","authors":"Weihong Liu ,&nbsp;Lingyu Zhu ,&nbsp;Xiaoqiang Zhuang ,&nbsp;Chendong Ding ,&nbsp;Yilu Zhao ,&nbsp;Chain Tsuan Liu ,&nbsp;Tao Yang ,&nbsp;Zhaoxuan Wu","doi":"10.1016/j.actamat.2025.120755","DOIUrl":"10.1016/j.actamat.2025.120755","url":null,"abstract":"<div><div>The presence or ingression of hydrogen (H) can dramatically embrittle a broad range of intrinsically ductile metals and alloys. Despite extensive research, fundamental understanding of hydrogen embrittlement (HE) and mitigation methods remain far from complete. Here, we present a thermodynamic approach to robustly enhance resistance to HE in CrCoNi with minor degradations of other properties. Specifically, 6 at.<span><math><mtext>%</mtext></math></span> W/Mo are doped and induced to segregate into grain boundary (GB) regions, which restores ductile transgranular fracture with dimpled fracture surfaces and tensile ductility losses of <span><math><mrow><mo>∼</mo><mn>10</mn><mo>−</mo><mn>30</mn><mtext>%</mtext></mrow></math></span> under gas-H-charged conditions. Density functional theory (DFT) calculations and Monte Carlo (MC) simulations reveal W-GB-segregation energies and favourable W-GB-segregations over a wide temperature window, as well as H-dissolution energies in grain interiors and GB regions. MC simulations with these DFT-based energetics show that most H-atoms reside in grain interiors in all alloys, but the GB-H-occupation ratios are <span><math><mrow><mo>∼</mo><mn>1</mn><mo>−</mo><mn>2</mn></mrow></math></span> orders-of-magnitude higher in the undoped alloy. In the doped alloys, W-GB-segregations moderately enhance GB cohesion and more importantly, make GB regions less attractive for H-dissolution, which in turn drastically reduces GB-H-occupation at the most critical low/room-temperatures. The stark differences in GB-H-occupation ratios in the doped and undoped alloys corroborate their respective void-coalescence and GB-cleavage dominant fracture mechanisms. The enhanced HE resistance is derived from GB-solute-segregation and reduced GB-H-occupation, both of which are thermodynamic equilibrium properties of the underlying alloy system. The combined experiments and simulations demonstrate a general strategy to design structural alloys for enhanced resistance to HE, which may be applicable to other alloy systems.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120755"},"PeriodicalIF":8.3,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143044528","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":"Machine learning-enabled design of ferroelectrics with multiple properties via a Landau model","authors":"Ruihao Yuan ,&nbsp;Bo Wang ,&nbsp;Jinshan Li ,&nbsp;Peng Sun ,&nbsp;Zhen Liu ,&nbsp;Xiangdong Ding ,&nbsp;Dezhen Xue ,&nbsp;Turab Lookman","doi":"10.1016/j.actamat.2025.120760","DOIUrl":"10.1016/j.actamat.2025.120760","url":null,"abstract":"<div><div>A physics based model often allows us to calculate several properties if the parameters for a given material are known. Here we address the question of making predictions of several properties from a Landau model for unexplored materials for which we do not know the material parameters. This is necessary if we are to predict new materials with targeted response with a physics based model than merely from data. We show how machine learning can be employed to learn parameters with an initial data set that need not be directly connected to the target properties. We demonstrate the approach by searching for BaTiO<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span>-based ceramics to predict properties relevant for the electrocaloric effect, dielectric tunability and pyroelectricity, starting from polarization and permittivity data only. The predictions are experimentally validated by synthesizing eight ceramics with a combination of competing properties, such as large adiabatic temperature change and wide temperature window at given temperatures. Five of the compounds show enhanced refrigeration capacity, outperforming reported counterparts. The approach shows promise for problems where adequate physics based models are available and there is limited data for properties.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120760"},"PeriodicalIF":8.3,"publicationDate":"2025-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143030803","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":"Simultaneous realization of giant d33, large kp, and high Qm from periodic interface strain generated by co-doping strategy","authors":"Xiaolin Huang, Bohan Xing, Yu Wang, Mingxuan Liu, Xing Wen, Xinyu Jin, Danyang Li, Peng Tan, Hao Tian","doi":"10.1016/j.actamat.2025.120770","DOIUrl":"https://doi.org/10.1016/j.actamat.2025.120770","url":null,"abstract":"However, achieving a well-balanced performance in environment-friendly lead-free piezoelectrics remains challenging as they still fall short of their lead-based counterparts owing to the unclear promotional origins of doping modification. We propose an ion co-doping strategy that simultaneously optimizes the piezoelectricity, electromechanical performance, mechanical quality factor, and electrical anti-fatigue in KTa₁₋<em>_x</em>Nb<em>_x</em>O₃ (KTN) single crystals. Further, the mechanism underlying the enhancement of these properties is elucidated. Microscopic and mesoscopic evidence demonstrate a more uniform order parameter induced by the co-doping defect structures, thereby yielding hierarchical domains and ordered lattice planes. At the atomic scale, the periodic interface strain induced by Mn and Fe co-doping orders the atomic arrangements, thereby stabilizing the polarization and domain states. Thus, the advantageous functions of both Mn and Fe ions are maintained. The superior overall properties of the co-doped KTN reach the level of lead-based single crystals. This work provides valuable insights into achieving piezoelectrics with excellent comprehensive performances using a co-doping strategy, while also advancing the understanding of how defect structures improve piezoelectric properties.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"8 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2025-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143031306","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":"A robust modeling framework for predicting nanovoid structures and energetics in FCC metals","authors":"Xiang-Shan Kong ,&nbsp;Liang Chen ,&nbsp;Tianli Su ,&nbsp;Jie Hou ,&nbsp;Zhiyong Zhang ,&nbsp;Jun Lin ,&nbsp;Guoqun Zhao ,&nbsp;Cunsheng Zhang ,&nbsp;Zhao Qian ,&nbsp;Rajeev Ahuja","doi":"10.1016/j.actamat.2025.120775","DOIUrl":"10.1016/j.actamat.2025.120775","url":null,"abstract":"<div><div>Understanding the structures and energetics of vacancy-type defects is crucial for comprehending defect evolution in metals, yet current methods face significant challenges, particularly regarding nanovoids in FCC metals. Here, we developed a robust modeling framework to accurately predict the structure and energetics of nanovoids in FCC metals. We demonstrated that stable nanovoid structures can be efficiently determined by maximizing the coordination number among vacancies and identified a linear relationship between nanovoid formation energies and their compactness factors. Notably, we revealed six discrete binding energy levels in nanovoid–vacancy interactions, each correlated solely with changes in compactness factors. Our new model has been validated through first-principles calculations and experiments, demonstrating clear advantages over conventional methods. This model effectively handles arbitrarily sized nanovoids in FCC metals, capturing atomic-scale variations, and providing key insights into vacancy-related damage, along with essential tools for multiscale modeling and the development of new metal interatomic potentials.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120775"},"PeriodicalIF":8.3,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143026910","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":"Understanding the competitive nanostructure evolution in V-doped hard metals by in-situ small-angle neutron scattering and thermodynamic-based modelling","authors":"Ahmet Bahadir Yildiz ,&nbsp;Manon Bonvalet Rolland ,&nbsp;R. Prasath Babu ,&nbsp;Robert Cubitt ,&nbsp;Susanne Norgren ,&nbsp;Peter Hedström","doi":"10.1016/j.actamat.2025.120773","DOIUrl":"10.1016/j.actamat.2025.120773","url":null,"abstract":"<div><div>Grain coarsening inhibition in hard metals is regarded as controlled by formation of interface complexions. To date, however, direct experimental insights into the presence and evolution of interface complexions during sintering of hard metals have been lacking. We here present <em>in-situ</em> small-angle neutron scattering (SANS) experiments up to 1500 °C and provide first-hand evidence on the thickness and volume fraction evolution of (V,W)C_x interface complexions in V-doped hard metals at various sintering temperatures. The experimental data is complemented by simulations using a thermodynamic-based model to understand the mechanisms behind the nanostructure evolution. We show that there indeed exist (V,W)C_x interface complexions at liquid-phase sintering temperatures; and their thickness and volume fraction are strongly related to the presence of bulk (V,W)C_x precipitation, the V activity in the Co-rich binder phase, and the temperature. The thermodynamics-based model, including the geometry of the investigated material system, reveals that the formation of (V,W)C_x bulk precipitates is energetically favorable over the thickening of complexions in the stability range of bulk precipitation. This, explains the reduction in complexion volume fraction and thickness with increasing temperature up to the dissolution of bulk precipitates. Upon dissolution of bulk precipitates, enhanced interfacial layer formation occurs through the formation of new layers of lower thickness, leading to better coverage of WC grains. The provided understanding of the nanostructure evolution during sintering is expected to foster the further development of representative modelling tools.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"287 ","pages":"Article 120773"},"PeriodicalIF":8.3,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143026911","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Plasticity of metallic glasses dictated by their state at the fragile-to-strong transition temperature","authors":"Achraf Atila,&nbsp;Sergey V. Sukhomlinov,&nbsp;Marc J. Honecker,&nbsp;Martin H. Müser","doi":"10.1016/j.actamat.2025.120753","DOIUrl":"10.1016/j.actamat.2025.120753","url":null,"abstract":"<div><div>The effect of cooling on the plasticity of glasses in general, and bulk metallic glasses (BMGs) in particular, is usually studied with continuously varying cooling rates; slower cooling rates lead to stiffer, harder, and more brittle glasses than higher cooling rates. These protocols obscure any potential discontinuity that a glass might experience, depending on whether its microstructure resembles that of a fragile or a strong glass-forming liquid. Here, we use large-scale molecular dynamics to simulate the nanoindentation behavior of model BMGs (Zr_0.6Cu_0.3Al_0.1) obtained by rapidly quenching equilibrium melts from temperatures above and below the fragile-to-strong transition temperature <span><math><msub><mrow><mi>T</mi></mrow><mrow><mtext>fst</mtext></mrow></msub></math></span>, leading to fragile and strong glasses, respectively. While the contact modulus deduced from the indentation simulation evolves smoothly with the temperature <span><math><msub><mrow><mi>T</mi></mrow><mrow><mtext>q</mtext></mrow></msub></math></span> from which the equilibrium melt is quenched, the plastic response changes quasi-discontinuously as <span><math><msub><mrow><mi>T</mi></mrow><mrow><mtext>q</mtext></mrow></msub></math></span> passes through <span><math><msub><mrow><mi>T</mi></mrow><mrow><mtext>fst</mtext></mrow></msub></math></span>. In particular, strong glasses develop highly asymmetric flow profiles with mature shear bands, unlike fragile glasses. Differences are most evident in the von Mises strain localization parameter, which, after shear-band formation, takes similar values for all fragile samples and distinct values for strong samples. Moreover, seemingly erratic flow profiles for our indentation geometry produced surprisingly reproducible and, thus, deterministic features. It remains to be determined to what extent other classes of glass formers follow our observation that plastic behavior is significantly influenced by whether the melt is fragile or strong when it falls out of equilibrium during cooling.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120753"},"PeriodicalIF":8.3,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143026427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermally-driven structural inhomogeneity and serrated plastic flow in TaTiZr amorphous medium-entropy alloy","authors":"W.J. Sun,&nbsp;T.Q. Li,&nbsp;Y.Q. Wang,&nbsp;J.D. Zuo,&nbsp;H.X. Zong,&nbsp;J.Y. Zhang,&nbsp;G. Liu,&nbsp;J. Sun","doi":"10.1016/j.actamat.2025.120764","DOIUrl":"10.1016/j.actamat.2025.120764","url":null,"abstract":"<div><div>Thermally driven structural heterogeneity, plastic deformation and concomitantly serration flow behavior in an equiatomic TaTiZr amorphous medium-entropy alloy (AMEA) were investigated systematically via experiment and simulation methods. The element segregation induced structural heterogeneity and short/medium-range ordering could be dramatically enhanced during heating below glassy temperature, owing to the annihilation of atomic free volume and structural relaxation. The uniaxial compression of TaTiZr AMEA micropillars exhibited an increasing yield strength with raising the annealing temperature, corresponding to a transformation of deformation behavior from homogeneous-like multiple shear banding to highly localized shear banding. Moreover, the statistical and dynamic analysis on the serrated stress-time curves of the as-deposited and annealed TaTiZr AMEAs demonstrated that both the stress drop amplitudes and their time durations are gradually decreased with annealing temperature. However, the corresponding distribution changes from a power-law scaling to a Gaussian behavior, indicating the transformation of underlying dynamics from a self-organized criticality to a chaotic state and the plastic deterioration in AMEAs due to the structural heterogeneity. The plastic deformation behavior and physical mechanism contributing to the serrated flow dynamics are rationalized in accordance with the mean-field theory. Our findings are expected to facilitate the understanding of the dynamic mechanism tuning intermittent flow of AMEAs to achieve exceptional deformation stability.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120764"},"PeriodicalIF":8.3,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143026425","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":"Harvesting superior intrinsic plasticity in nitride ceramics with negative stacking fault energy","authors":"Yong Huang ,&nbsp;Zhuo Chen ,&nbsp;Michael Meindlhumer ,&nbsp;Rainer Hahn ,&nbsp;David Holec ,&nbsp;Thomas Leiner ,&nbsp;Verena Maier-Kiener ,&nbsp;Yonghui Zheng ,&nbsp;Zequn Zhang ,&nbsp;Lukas Hatzenbichler ,&nbsp;Helmut Riedl ,&nbsp;Christian Mitterer ,&nbsp;Zaoli Zhang","doi":"10.1016/j.actamat.2025.120774","DOIUrl":"10.1016/j.actamat.2025.120774","url":null,"abstract":"<div><div>Ceramics face an everlasting challenge from their intrinsic brittleness at room temperature, which can lead to early-stage catastrophic failures. The fatal disadvantage primarily results from the high critical-resolved shear stress required to initiate dislocation movement and the limited number of operational slip systems. Here, we propose a new strategy for designing deformable ceramics by negative stacking fault energy (SFE), which realizes energetic barrier reduction of dislocation motion and slip system expansion. This way, we harvested a superior room-temperature compressive plasticity in TiN/TaN superlattice by successive and extensive atomic plane faulting and twinning. This strategy sheds light on the design of intrinsically ductile ceramics.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120774"},"PeriodicalIF":8.3,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143020078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Size-dependent fragment shape in high-velocity anvil impact of spherical metal powder-compacts","authors":"Gary Simpson ,&nbsp;Jesse Grant ,&nbsp;Timothy P. Weihs ,&nbsp;K.T. Ramesh","doi":"10.1016/j.actamat.2024.120647","DOIUrl":"10.1016/j.actamat.2024.120647","url":null,"abstract":"<div><div>Room-temperature mechanical swaging of metallic powders allows the flexible synthesis of fully consolidated, composite powder compacts that can retain nearly the full strength, toughness, density, and machinability of their bulk parent elements. The swaging process offers the ability to compositionally tailor a material to exploit reactive inter-phase chemistry. Unlike some other cold powder-metallurgy fabrication methods, though, it can produce mechanically competent materials capable of serving in structurally useful applications. By means of fragment soft-catch and recovery, we evaluate the effects of initial powder size and degree of mechanical swaging on the impact fragmentation statistics of pure aluminum powder-swaged projectiles. Here, processing alone induces a wide range of impact fragmentation behavior, generally correlating with the effective toughness of the swaged product. As such, we interrogate the dynamic fragmentation of both brittle and tough metals across this range without varying composition. We observe a clear relationship between fragment size and shape, utilizing this relationship to improve high-throughput optical measurements of volume-weighted fragment size. We find surprisingly similar average fragment shape to previous hypervelocity impact experiments on geological materials, suggesting some common underlying mechanical patterns of fragmentation in the ballistic impact of otherwise disparate materials. Furthermore, post-mortem analysis suggests that the selection of appropriate starting particle size and degree of swaging in rotary-swaged metals provides some distinct and potentially valuable ability to tune dynamic fragmentation, in comparison to that of the wrought metal, while maintaining suitably high quasi-static toughness and ductility for engineering purposes.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120647"},"PeriodicalIF":8.3,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143026424","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":"Unique twinning mode and extended twin boundary core structure associated with symmetry breaking in a multifunctional Ti-Nb-based alloy","authors":"Yipeng Gao ,&nbsp;Jiyuan Ding ,&nbsp;Chunfeng Du ,&nbsp;Dian Li ,&nbsp;Qianglong Liang ,&nbsp;Yufeng Zheng ,&nbsp;Dong Wang ,&nbsp;Hamish L. Fraser ,&nbsp;Hui-Yuan Wang ,&nbsp;Yunzhi Wang","doi":"10.1016/j.actamat.2025.120769","DOIUrl":"10.1016/j.actamat.2025.120769","url":null,"abstract":"<div><div>Recently, a class of multifunctional Ti-Nb-based alloys has been developed, exhibiting exceptional mechanical and physical properties, such as high strength, high ductility, low-modulus superelasticity, and Invar/Elinvar anomalies. These properties are closely linked to the co-evolution of various microstructural defects, including dislocations, twins, and second-phase domains. In this study, we show the formation of unique defects, such as {3 9 10} twins and extended twin boundary core structures, in a cold-rolled Ti-24Nb-4Zr-8Sn-0.2O (wt.%) alloy. These defects arise from the intrinsic coupling between phase transformation and deformation twinning. Using a phase transition graph approach, we demonstrate that these high-index twins and extended defect core structures originate from the correlated broken symmetry associated with multiple crystal deformation processes. By establishing a symmetry-based link between deformation paths and characteristic defects, our work offers a new perspective for investigating the deformation mechanisms and unique properties of metallic materials.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120769"},"PeriodicalIF":8.3,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143026426","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}