Acta Materialia最新文献

{"title":"Spontaneous spin and valley polarizations in novel RuO2(MgF)2 and RuO2(ZnF)2 ferrovalley semiconductors with ultrahigh Curie temperatures","authors":"Kang Sheng,&nbsp;Zhi-Yong Wang","doi":"10.1016/j.actamat.2025.120988","DOIUrl":"10.1016/j.actamat.2025.120988","url":null,"abstract":"<div><div>Two-dimensional room-temperature (RT) ferrovalley semiconductors with spontaneous spin and valley polarizations hold enormous potential in next-generation high-speed and low-power dissipation information technology. By first-principles calculations and Monte Carlo simulations, we discover that the RuO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>(MgF)<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> and RuO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>(ZnF)<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> monolayers with viable fabrication are right such extremely scarce candidate materials. In particular, both RuO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>(MgF)<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> and RuO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>(ZnF)<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> are predicted to be Ising-type ferromagnets with ultrahigh Curie temperatures of 1084 and 972 K, respectively. Due to the interplay between spin–orbital coupling and out-of-plane ferromagnetism, the hexagonal RuO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>(MgF)<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>/RuO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>(ZnF)<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> motif spontaneously produces ultraclean valley polarizations as sizable as 195/194 meV in their topmost valence bands, which are further corroborated by a four-band <em>k</em> <span><math><mi>⋅</mi></math></span> <em>p</em> model. More importantly, these two materials remain as above-RT Ising ferromagnets under both hole doping and biaxial strains within experimental reach. The anomalous valley Hall effect can be naturally achieved in both systems through doping moderate holes and infrared light irradiation upon applying an in-plane electric field. Also, we find that the spin and valley polarizations can be inverted via compressive strain and magnetization flipping. These outstanding attributes expose vast potential of both RuO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>(MgF)<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> and RuO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>(ZnF)<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> for a broad range of potential applications in straintronics, spintronics, valleytronics, optoelectronics and their integration.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"291 ","pages":"Article 120988"},"PeriodicalIF":8.3,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143814839","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 guided design of RE-Fe-B(RE=PrNd,La,Ce) with comprehensive high performance","authors":"Zheng Wang ,&nbsp;Shiyi Zhang ,&nbsp;Jing Wang ,&nbsp;Ming Zhang ,&nbsp;Yunzhong Chen ,&nbsp;Baohe Li ,&nbsp;Tongyun Zhao ,&nbsp;Minggang Zhu ,&nbsp;Fengxia Hu ,&nbsp;Baogen Shen ,&nbsp;Wei Li","doi":"10.1016/j.actamat.2025.121031","DOIUrl":"10.1016/j.actamat.2025.121031","url":null,"abstract":"<div><div>The optimization of high-abundance REFeB (RE=PrNd,La,Ce) permanent magnets has been a significant research focus, but traditional trial-and-error methods are challenging due to high costs and time consumption. Here, we propose a machine-learning approach to accelerate the design of melt-spun high-abundance (PrNd,La,Ce)-Fe-B ribbons based on the database incorporating elemental electronegativity with the composition and magnetic performance collected from literature. By combining heuristic optimization algorithms and ensemble strategies, we developed accurate and robust machine learning models, allowing for rapid evaluation of comprehensive magnetic performance across different compositions in high-dimensional data spaces and discovering high-performance REFeB permanent magnets with high-abundance rare earth elements. Utilizing the established models, by balancing three magnetic properties of coercivity, remanence and maximum magnetic energy product, we discovered a compositional range with optimal overall magnetic performance and high proportions of high-abundance rare earth elements (up to 40 % La and 20 % Ce of the total rare earth content) for the magnets of (PrNd_xLa_yCe_1-x-y)₁₂Fe₈₂B₆, which were verified by experiments with accuracies exceeding 90 %. Within this range, four cost-effective compositions were identified, among which the best composition, (Pr,Nd)_8.1La_3.6Ce_0.3Fe₈₂B₆, achieved a 31.3 % cost reduction while retaining 86.4 % of the magnetic performance. This study advances the optimization of REFeB compositions with high-abundance rare earth elements, demonstrating the enormous potential of machine-learning approach in the design and development of high-performance and cost-effective REFeB permanent magnets.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"292 ","pages":"Article 121031"},"PeriodicalIF":8.3,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143814345","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":"Apatite-type gadolinium-based dense MGd4Si3O13 (M = Mg, Ca, and Sr) ceramics: An emerging class of sub-liquid helium temperature magnetic refrigerant","authors":"Yikun Zhang ,&nbsp;Angsai Li ,&nbsp;Weixiang Hao ,&nbsp;Hai-Feng Li ,&nbsp;Lingwei Li","doi":"10.1016/j.actamat.2025.121033","DOIUrl":"10.1016/j.actamat.2025.121033","url":null,"abstract":"<div><div>Low-temperature magnetic refrigeration (MR), based on the magnetocaloric (MC) effect of magnetic materials, is recognized as a distinct and powerful cooling technology. We herein introduce a class of promising low-temperature magnetic refrigerants: the apatite-type gadolinium-based dense <em>M</em>Gd₄Si₃O₁₃ (M = Mg, Ca, and Sr) ceramics. These ceramics exhibit giant MC effects and prominent performance in the sub-liquid helium temperature range. The maximum magnetic entropy change values of these ceramics are 59.5 and 32.2 J/kgK under magnetic fields of 0–7 and 0–2 T, respectively. These results surpass those of the commercial magnetic refrigerant gadolinium gallium garnet (GGG, ∼32.8 and 14.6 J/kgK) and are superior to most known benchmarked low-temperature magnetic refrigerants. Furthermore, these apatite-type gadolinium-based ceramics possess relatively high density (6.277∼6.562 g/cm³) and exhibit good environmental stability. These characteristics make these apatite-type <em>M</em>Gd₄Si₃O₁₃ ceramics highly suitable for practical sub-liquid helium temperature MR applications.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"292 ","pages":"Article 121033"},"PeriodicalIF":8.3,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143814176","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":"Capillary shrinkage induced ductile–brittle transition in nanoporous gold: Crack healing via cold welding","authors":"Zhi-Jie Lu ,&nbsp;Ling-Zhi Liu ,&nbsp;Hui Xie ,&nbsp;Hai-Jun Jin","doi":"10.1016/j.actamat.2025.120997","DOIUrl":"10.1016/j.actamat.2025.120997","url":null,"abstract":"<div><div>When a brittle nanoporous material infiltrated with water is dried in air, the capillarity-induced large volume shrinkage often leads to cracking within the material. In consequence, porous material may become more fragile or even shatter after drying. In this paper, we prepared nanoporous gold (NPG) with a low relative density by dealloying dilute Ag(Au) precursor alloys. Drying of this sample in air leads to a large volume contraction up to 22<span><math><mo>∼</mo></math></span>38%. Meanwhile, the material undergoes a ductile–brittle transition during drying: The wet sample of as-dealloyed NPG, while tested in water, shows a surprisingly large tensile strain up to 8%–10% before fracture; After drying, the fracture strain of the same material drops to around 1% in tension. This ductile-to-brittle transition is not caused by the formation of cracks as usual. Instead, it can be linked to the self-healing of microcracks during drying. We found that the plasticity of as-dealloyed NPG arises from the presence of high-density native microcracks. The bridging or deflection of these microcracks in tension leads to a diffuse failure, which accounts for the large irreversible tensile strain of the wet, as-dealloyed NPG. Further examination reveals that these native microcracks can be healed during drying, owing to the cold welding of nano-ligaments under capillary contraction force. Healing of these microcracks suppresses the diffuse failure induced by crack bridging or deflection, leading to a brittle fracture of the dried NPG in tension. Cold welding of nano-ligaments, which accounts for the anomalous crack healing and ductile–brittle transition of NPG in drying, might occur frequently in nanoporous metals under external load and contribute significantly to their mechanical performance.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"292 ","pages":"Article 120997"},"PeriodicalIF":8.3,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143814177","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":"Surface reconstruction and band alignment of non-metallic spinel oxides from first principles","authors":"Tianwei Wang, Nobuya Sato, Fumiyasu Oba","doi":"10.1016/j.actamat.2025.121034","DOIUrl":"https://doi.org/10.1016/j.actamat.2025.121034","url":null,"abstract":"A systematic prediction of the reconstructed surfaces of non-metallic normal spinel oxides is conducted using a global structure search scheme that combines Bayesian optimisation and the evolutionary algorithm, adopting first principles calculations for local optimisations. Their (100) surfaces with macroscopically stoichiometric and nonpolar terminations are investigated, yielding various representative reconstructed surface geometries for &lt;span&gt;&lt;span style=\"\"&gt;&lt;/span&gt;&lt;span data-mathml='&lt;math xmlns=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;mrow is=\"true\"&gt;&lt;msup is=\"true\"&gt;&lt;mrow is=\"true\"&gt;&lt;mi is=\"true\"&gt;A&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow is=\"true\"&gt;&lt;mn is=\"true\"&gt;2&lt;/mn&gt;&lt;mo is=\"true\"&gt;+&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;msubsup is=\"true\"&gt;&lt;mi is=\"true\"&gt;B&lt;/mi&gt;&lt;mn is=\"true\"&gt;2&lt;/mn&gt;&lt;mrow is=\"true\"&gt;&lt;mn is=\"true\"&gt;3&lt;/mn&gt;&lt;mo is=\"true\"&gt;+&lt;/mo&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;msub is=\"true\"&gt;&lt;mi mathvariant=\"normal\" is=\"true\"&gt;O&lt;/mi&gt;&lt;mn is=\"true\"&gt;4&lt;/mn&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;' role=\"presentation\" style=\"font-size: 90%; display: inline-block; position: relative;\" tabindex=\"0\"&gt;&lt;svg aria-hidden=\"true\" focusable=\"false\" height=\"3.24ex\" role=\"img\" style=\"vertical-align: -0.928ex;\" viewbox=\"0 -995.6 4751.2 1395\" width=\"11.035ex\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"&gt;&lt;g fill=\"currentColor\" stroke=\"currentColor\" stroke-width=\"0\" transform=\"matrix(1 0 0 -1 0 0)\"&gt;&lt;g is=\"true\"&gt;&lt;g is=\"true\"&gt;&lt;g is=\"true\"&gt;&lt;g is=\"true\"&gt;&lt;use xlink:href=\"#MJMATHI-41\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;/g&gt;&lt;g is=\"true\" transform=\"translate(750,443)\"&gt;&lt;g is=\"true\"&gt;&lt;use transform=\"scale(0.707)\" xlink:href=\"#MJMAIN-32\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;g is=\"true\" transform=\"translate(353,0)\"&gt;&lt;use transform=\"scale(0.707)\" xlink:href=\"#MJMAIN-2B\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;/g&gt;&lt;/g&gt;&lt;g is=\"true\" transform=\"translate(1754,0)\"&gt;&lt;g is=\"true\"&gt;&lt;use xlink:href=\"#MJMATHI-42\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;g is=\"true\" transform=\"translate(759,403)\"&gt;&lt;g is=\"true\"&gt;&lt;use transform=\"scale(0.707)\" xlink:href=\"#MJMAIN-33\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;g is=\"true\" transform=\"translate(353,0)\"&gt;&lt;use transform=\"scale(0.707)\" xlink:href=\"#MJMAIN-2B\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;/g&gt;&lt;g is=\"true\" transform=\"translate(759,-308)\"&gt;&lt;use transform=\"scale(0.707)\" xlink:href=\"#MJMAIN-32\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;/g&gt;&lt;g is=\"true\" transform=\"translate(3518,0)\"&gt;&lt;g is=\"true\"&gt;&lt;use xlink:href=\"#MJMAIN-4F\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;g is=\"true\" transform=\"translate(778,-150)\"&gt;&lt;use transform=\"scale(0.707)\" xlink:href=\"#MJMAIN-34\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;/g&gt;&lt;/g&gt;&lt;/g&gt;&lt;/svg&gt;&lt;span role=\"presentation\"&gt;&lt;math xmlns=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;mrow is=\"true\"&gt;&lt;msup is=\"true\"&gt;&lt;mrow is=\"true\"&gt;&lt;mi is=\"true\"&gt;A&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow is=\"true\"&gt;&lt;mn is=\"true\"&gt;2&lt;/mn&gt;&lt;mo is=\"true\"&gt;+&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;msubsup is=\"true\"&gt;&lt;mi is=\"true\"&gt;B&lt;/mi&gt;&lt;mn is=\"true\"&gt;2&lt;/mn&gt;&lt;mrow is=\"true\"&gt;&lt;mn is=\"true\"&gt;3&lt;/mn&gt;&lt;mo is=\"true\"&gt;+&lt;/mo&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;msub is=\"true\"&gt;&lt;mi is=\"true\" mathvariant=\"normal\"&gt;O&lt;/mi&gt;&lt;mn is=\"true\"&gt;4&lt;/mn&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;&lt;/span&gt;&lt;script type=\"math/mml\"&gt;&lt;math&gt;&lt;m","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"4 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143814178","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 pre-corrosion strategy for ultra-stable Zn metal anodes via hybrid interface engineering","authors":"Chen Liu ,&nbsp;Jian Zeng ,&nbsp;Shuanlong Di ,&nbsp;Xinglong Li ,&nbsp;Shulan Wang ,&nbsp;Li Li","doi":"10.1016/j.actamat.2025.121025","DOIUrl":"10.1016/j.actamat.2025.121025","url":null,"abstract":"<div><div>Though aqueous Zn metal batteries are attractive considering their high capacities and safety, the short lifespan caused by severe dendrite growth and parasitic reactions strongly retard their practical use. Constructing regulated interfaces on Zn anodes shows great promise in addressing this issue but faces significant challenges in developing eco-friendly methods that can simultaneously protect Zn and homogenize metal deposition. Herein, we develop a straightforward pre-corrosion strategy for commercial Zn foil through a one-step immersion treatment. By using Al(NO₃)₃ as the sole etching reagent and structural-guiding template, a hybrid interface composed of aluminum hydroxide and oriented Zn was constructed. Strikingly, Zn (002)-textured surface after etching induces preferential orientation of Zn deposits with effective suppression of dendrite growth. Meanwhile, the thin interlayer with high zincophilicity and hydrophilicity reduces the nucleation overpotential and desolvation barrier, thereby ensuring rapid Zn²⁺ migration kinetics. The as-prepared electrode therefore showcases an ultra-long cycling lifespan over 2400 h at 1 mA cm⁻² (1100 % increase over that of bare Zn), along with a low overpotential (64 mV) even at 10 mA cm⁻². The full battery further proves remarkable cyclability (97.5 % capacity retention after 1800 cycles). This work provides new insights into advanced interface design for aqueous metal batteries.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"292 ","pages":"Article 121025"},"PeriodicalIF":8.3,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143820237","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":"Nanoparticle recrystallization: kinetics and size-dependent behavior","authors":"Jonathan Zimmerman,&nbsp;Eugen Rabkin","doi":"10.1016/j.actamat.2025.121028","DOIUrl":"10.1016/j.actamat.2025.121028","url":null,"abstract":"<div><div>Recrystallization of metals plays a central role in materials processing as it represents a primary tool for manipulating material microstructure and properties. However, recrystallization has not yet been employed for the synthesis of metal nanoparticles. In this work we describe the kinetics of recrystallization and related annealing phenomena in Pt nanoparticles. We uniaxially deformed the particles and annealed them both <em>in-situ</em> and <em>ex-situ</em> while characterizing their morphology and microstructure. Our findings reveal that new grains often nucleate within the parent particle, only to be rapidly reabsorbed back into it, with a strong correlation between this phenomenon and particle size. We propose a model that combines recrystallization and recovery through dislocation annihilation at the particle surface, predicting a critical size for recrystallization in nanoparticles. Finally, we propose a set of rules for nanoparticle recrystallization, mirroring the rules of recrystallization in bulk materials.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"292 ","pages":"Article 121028"},"PeriodicalIF":8.3,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143806497","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":"Non-equilibrium nanostructured permanent magnets with excellent magnetic properties over an exceptionally wide temperature range","authors":"Yuye Wu ,&nbsp;Xuefeng Liao ,&nbsp;Weiwei Zeng ,&nbsp;Konstantin Skokov ,&nbsp;Oliver Gutfleisch ,&nbsp;Haichen Wu ,&nbsp;Yuxiang Xiao ,&nbsp;Yichen Xu ,&nbsp;Xiaoxiao Wang ,&nbsp;Keyu Yan ,&nbsp;Yunquan Li ,&nbsp;Hai-Tian Zhang ,&nbsp;Qing Zhou ,&nbsp;Ying Dong ,&nbsp;Dazhuang Kang ,&nbsp;Chengbao Jiang","doi":"10.1016/j.actamat.2025.121029","DOIUrl":"10.1016/j.actamat.2025.121029","url":null,"abstract":"<div><div>Space exploration demands lightweight high-performance permanent magnets that are fully functional in a wide temperature range of 2∼450 K. However, Nd-Fe-B permanent magnets, which have the strongest room-temperature magnetic properties, are unsuitable for such applications because of their degraded performance at both elevated and cryogenic temperatures. It is well-established that substituting praseodymium enhances the low-temperature properties of these magnets, while cobalt substitution improves high-temperature stability. However, using conventional manufacturing techniques, it is virtually impossible to replace more than 10 % of iron with cobalt without a significant reduction in coercivity. Herein, we propose a non-equilibirum nanostructuring strategy, which is implemented by co-doping Pr and Co to attain a non-equilibrium microstructure with Co supersaturation in the matrix to overcome both the upper and lower temperature limitations. We constructed phase diagrams and operational temperature maps to determine the optimal composition and production temperature, resulting in a (Nd_0.2Pr_0.8)_13.6(Fe_0.75Co_0.25)_80.4Ga_0.5B_5.5 heavy-rare-earth-free permanent magnet with the desired properties. The operational temperature range is broadened from 135–350 K for ternary Nd-Fe-B magnets to 2–450 K for the (Nd_0.2Pr_0.8)_13.6(Fe_0.75Co_0.25)_80.4Ga_0.5B_5.5 magnet. The microstructural characterizations and micromagnetic simulations highlight the significance of non-equilibrium microstructures in this magnet, whereas the supersaturation of Co in the matrix and the suppression of unfavorable soft-magnetic phases are critical to realizing superior magnetic properties. The new non-equilibrium magnet plug the gap of high-performance magnet for space explorations, and the non-equilibrium nanostructuring strategy offers new possibilities for designing magnets with unprecedented properties.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"292 ","pages":"Article 121029"},"PeriodicalIF":8.3,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143806495","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 insights into iron-based phase transformation oxides for highly efficient thermochemical water splitting","authors":"Dongkyu Lee ,&nbsp;Hyeokjoon June ,&nbsp;Byeong-Gyu Park ,&nbsp;Joo-Hee Kang ,&nbsp;Taehyeong Kim ,&nbsp;Jeong Woo Han ,&nbsp;Hyungyu Jin","doi":"10.1016/j.actamat.2025.121023","DOIUrl":"10.1016/j.actamat.2025.121023","url":null,"abstract":"<div><div>Two-step thermochemical water splitting (TWS) is a promising green hydrogen production technology in which metal oxides are used as redox-active materials to split steam. Among the several challenges toward the commercialization of two-step TWS, the limited performance of existing redox materials has been identified as a critical issue. Here, we report Fe-poor Ni ferrites (NFOs), a class of phase transformation oxides, as highly promising redox materials for two-step TWS that overcome the limitations of existing materials. These materials achieve a superior H₂O-to-H₂ conversion of 0.528 %/g_oxide under more favorable reaction conditions, outperforming state-of-the-art materials that exhibit &lt; 0.250 %/g_oxide. A redox-active cation in Fe-poor NFOs is hypothesized and experimentally validated, establishing the fundamental structure-property relationships. Our results show that the extent of redox swing between the two active cations strongly correlates with water splitting performance. Density functional theory calculations reveal that both the number of active sites and the surface reaction energy play critical roles in determining the redox swing extent and, consequently, the water splitting performance. This study not only introduces Fe-poor NFOs as new state-of-the-art materials for two-step TWS, but also provides fundamental insights that can be broadly applied in the design of highly efficient redox oxides.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"292 ","pages":"Article 121023"},"PeriodicalIF":8.3,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143806496","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":"Designing high ductility TiAl alloys based on dislocation nucleation mechanism","authors":"Shiping Wang ,&nbsp;Demin Zhu ,&nbsp;Zhongtao Lu ,&nbsp;Xiaobin Feng ,&nbsp;Wenjuan Li ,&nbsp;Pengcheng Zhai ,&nbsp;Yang Chen ,&nbsp;Guodong Li ,&nbsp;Zhixiang Qi ,&nbsp;Guang Chen","doi":"10.1016/j.actamat.2025.121027","DOIUrl":"10.1016/j.actamat.2025.121027","url":null,"abstract":"<div><div>The yield strength and ductility of nanoscale biphasic materials are governed by the critical resolved shear stress (CRSS) for dislocation nucleation. Polysynthetic twinned (PST) TiAl single crystals with alternating layers of γ-TiAl and α₂-Ti₃Al exhibit high yield strength and ductility at room temperature. However, the relationship between its high performance and dislocation nucleation mechanism has not been clearly understood. In this work, we investigated the influence of the interfacial dislocations and the normal stress of slip plane on dislocation nucleation in the γ-TiAl/α₂-Ti₃Al alloys via biaxial loading using molecular dynamics simulations. Three types of dislocations were observed in the initial yielding stage, including <span><math><mrow><mrow><mo>{</mo><mn>111</mn><mo>}</mo></mrow><mo>&lt;</mo><mn>11</mn><mover><mrow><mn>2</mn></mrow><mo>‾</mo></mover><mtext>]</mtext></mrow></math></span> twin dislocation and <span><math><mrow><mrow><mo>{</mo><mn>111</mn><mo>}</mo></mrow><mo>&lt;</mo><mover><mrow><mn>1</mn></mrow><mo>‾</mo></mover><mn>01</mn><mtext>]</mtext></mrow></math></span> superlattice dislocation for γ-TiAl, <span><math><mrow><mrow><mo>{</mo><mn>1</mn><mover><mrow><mn>1</mn></mrow><mo>‾</mo></mover><mn>00</mn><mo>}</mo></mrow><mo>&lt;</mo><mn>11</mn><mover><mrow><mn>2</mn></mrow><mo>‾</mo></mover><mn>0</mn><mo>&gt;</mo></mrow></math></span> prismatic dislocation for α₂-Ti₃Al. The analysis for the yield conditions revealed that there is an approximate linear relation between the resolved shear stress and resolved normal stress for the three types of slip systems, which is consistent with the results of first principles. We proposed a design strategy for high ductility TiAl alloys based on this relationship, which involves introducing stress differences between the CRSS of two phases through pre-stressing. To verify the effectiveness of this strategy in practical applications, we applied pre-compression to the PST TiAl single crystal to introduce the difference in strength between the two phases, which led to crack uniformly occurring in γ phase but limiting in α₂ phase, finally increasing the elongation of PST TiAl single crystal by about 300 %.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"292 ","pages":"Article 121027"},"PeriodicalIF":8.3,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143798367","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}