Pub Date : 2026-01-10DOI: 10.1016/j.actamat.2026.121925
Wei Shao , Yi Yang , Jan S. Wróbel , Javier LLorca
The interface free energies at A/B (A=Al and θ′′, B=θ′′ and θ′) interfaces were determined as a function of temperature by means of first-principles and phonon calculations within the framework of harmonic and quasi-harmonic approximations. The interface free energies of five interfaces - Al(001)||θ′′(001), Al(001)||θ′(001), θ′′(001)||θ′(001), Al(010)||θ′′(010) and Al(010)||θ′(010) - decreased with increasing temperature as a result of the vibrational entropic contribution. Furthermore, it was found that effect of thermal expansion on the interface free energy is negligible for the Al(001)||θ′′(001), Al(001)||θ′(001) and Al(010)||θ′(010) interface, while it will lead to an increase or decrease in interface free energy of Al(010)||θ′′(010) or θ′′(001)||θ′(001), respectively. The differences in the temperature dependence of interfacial free energies among the five interfaces can be attributed to variations in stretching stiffness resulting from changes in bond lengths and the proportion of Al-Al and Al-Cu bonds in each interface. This study provides atomistic insights into temperature-dependent interfacial free energy and motivates future work extending this approach to more complex systems.
{"title":"Temperature dependence of the interface energy in Al-Cu alloys from first-principles and phonon calculations","authors":"Wei Shao , Yi Yang , Jan S. Wróbel , Javier LLorca","doi":"10.1016/j.actamat.2026.121925","DOIUrl":"10.1016/j.actamat.2026.121925","url":null,"abstract":"<div><div>The interface free energies at A/B (<em>A</em>=Al and θ′′, <em>B</em>=θ′′ and θ′) interfaces were determined as a function of temperature by means of first-principles and phonon calculations within the framework of harmonic and quasi-harmonic approximations. The interface free energies of five interfaces - Al(001)||θ′′(001), Al(001)||θ′(001), θ′′(001)||θ′(001), Al(010)||θ′′(010) and Al(010)||θ′(010) - decreased with increasing temperature as a result of the vibrational entropic contribution. Furthermore, it was found that effect of thermal expansion on the interface free energy is negligible for the Al(001)||θ′′(001), Al(001)||θ′(001) and Al(010)||θ′(010) interface, while it will lead to an increase or decrease in interface free energy of Al(010)||θ′′(010) or θ′′(001)||θ′(001), respectively. The differences in the temperature dependence of interfacial free energies among the five interfaces can be attributed to variations in stretching stiffness resulting from changes in bond lengths and the proportion of Al-Al and Al-Cu bonds in each interface. This study provides atomistic insights into temperature-dependent interfacial free energy and motivates future work extending this approach to more complex systems.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"306 ","pages":"Article 121925"},"PeriodicalIF":9.3,"publicationDate":"2026-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145947508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-09DOI: 10.1016/j.actamat.2026.121918
Lucas M. Ruschel , Bastian Adam , Oliver Gross , Maximilian Frey , Nico Neuber , Fan Yang , Ralf Busch
This study investigates the glass-forming ability of Ni–Nb–P-based bulk metallic alloys through a systematic analysis of their thermodynamic, kinetic, and crystallization behavior. Differential scanning calorimetry, viscosity measurements, and in-situ synchrotron X-ray diffraction were employed to examine three compositions: Ni62Nb38, Ni59.2Nb38.8P2 and Ni59.2Nb33.8Ta5P2. While all alloys exhibit a high thermodynamic driving force for crystallization, the phosphorus- and tantalum-containing variants demonstrate significantly improved glass-forming ability. This improvement is linked to increased viscosity and suppression of primary crystallization. In particular, the addition of phosphorus promotes the formation of a phosphorus-rich intermetallic phase that requires long-range diffusion, delaying crystallization. The combined kinetic slowdown and delayed phase formation sufficiently retard crystallization, allowing fully amorphous samples up to 6 mm in diameter to be produced, compared to 2 mm for binary Ni–Nb. These findings highlight how judicious micro-alloying can enhance glass-forming ability through kinetic control of the crystallization pathway.
本研究通过系统分析ni - nb - p基大块金属合金的热力学、动力学和结晶行为，研究了其玻璃化形成能力。采用差示扫描量热法、粘度测量法和原位同步x射线衍射法对Ni62Nb38、Ni59.2Nb38.8P2和Ni59.2Nb33.8Ta5P2三种成分进行了表征。虽然所有合金都表现出较高的结晶热力学驱动力，但含磷和含钽的合金变体显示出明显改善的玻璃形成能力。这种改善与粘度的增加和初级结晶的抑制有关。特别是，磷的加入促进富磷金属间相的形成，需要远距离扩散，延迟结晶。结合动力学减速和延迟相形成充分延缓结晶，允许生产直径达6毫米的完全非晶样品，而二元Ni-Nb则为2毫米。这些发现强调了合理的微合金化可以通过动力学控制晶化途径来提高玻璃形成能力。
{"title":"Assessment of the thermodynamics, kinetics and crystallization sequence of Ni–Nb–P-based bulk metallic glass-forming alloys","authors":"Lucas M. Ruschel , Bastian Adam , Oliver Gross , Maximilian Frey , Nico Neuber , Fan Yang , Ralf Busch","doi":"10.1016/j.actamat.2026.121918","DOIUrl":"10.1016/j.actamat.2026.121918","url":null,"abstract":"<div><div>This study investigates the glass-forming ability of Ni–Nb–P-based bulk metallic alloys through a systematic analysis of their thermodynamic, kinetic, and crystallization behavior. Differential scanning calorimetry, viscosity measurements, and in-situ synchrotron X-ray diffraction were employed to examine three compositions: Ni<sub>62</sub>Nb<sub>38</sub>, Ni<sub>59.2</sub>Nb<sub>38.8</sub>P<sub>2</sub> and Ni<sub>59.2</sub>Nb<sub>33.8</sub>Ta<sub>5</sub>P<sub>2</sub>. While all alloys exhibit a high thermodynamic driving force for crystallization, the phosphorus- and tantalum-containing variants demonstrate significantly improved glass-forming ability. This improvement is linked to increased viscosity and suppression of primary crystallization. In particular, the addition of phosphorus promotes the formation of a phosphorus-rich intermetallic phase that requires long-range diffusion, delaying crystallization. The combined kinetic slowdown and delayed phase formation sufficiently retard crystallization, allowing fully amorphous samples up to 6 mm in diameter to be produced, compared to 2 mm for binary Ni–Nb. These findings highlight how judicious micro-alloying can enhance glass-forming ability through kinetic control of the crystallization pathway.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"306 ","pages":"Article 121918"},"PeriodicalIF":9.3,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145973779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-09DOI: 10.1016/j.actamat.2026.121916
Junjie Cao , Liping Guo , Yiheng Chen , Congxiao Liu , Rui Yan , Hongtai Luo
An analytical model is presented that characterizes the evolution of irradiation-induced dislocation loops in ferritic/martensitic (F/M) steels. The model establishes quantitative relationships among microstructural changes, irradiation conditions, and mechanical properties, predicting both dislocation loop behavior and irradiation hardening. Analysis indicates that the density of a/2<111> loops decreases with increasing temperature over 250 °C, whereas a<100> loops peak at approximately 450 °C before declining. Both loop types exhibit saturation at high irradiation doses, and their size distributions are well described by a log-normal function. An L-shaped phase diagram identifies a transition region between 350-400 °C, reflecting a shift in the dominant dislocation loop type. The model’s explicit functional relationships provide a basis for optimizing the design and performance of F/M steels in advanced nuclear systems, potentially contributing to enhanced irradiation resistance and material reliability.
{"title":"First phase diagram of dislocation loops achieved through an innovative analytical framework","authors":"Junjie Cao , Liping Guo , Yiheng Chen , Congxiao Liu , Rui Yan , Hongtai Luo","doi":"10.1016/j.actamat.2026.121916","DOIUrl":"10.1016/j.actamat.2026.121916","url":null,"abstract":"<div><div>An analytical model is presented that characterizes the evolution of irradiation-induced dislocation loops in ferritic/martensitic (F/M) steels. The model establishes quantitative relationships among microstructural changes, irradiation conditions, and mechanical properties, predicting both dislocation loop behavior and irradiation hardening. Analysis indicates that the density of a/2<111> loops decreases with increasing temperature over 250 °C, whereas a<100> loops peak at approximately 450 °C before declining. Both loop types exhibit saturation at high irradiation doses, and their size distributions are well described by a log-normal function. An L-shaped phase diagram identifies a transition region between 350-400 °C, reflecting a shift in the dominant dislocation loop type. The model’s explicit functional relationships provide a basis for optimizing the design and performance of F/M steels in advanced nuclear systems, potentially contributing to enhanced irradiation resistance and material reliability.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"306 ","pages":"Article 121916"},"PeriodicalIF":9.3,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145974295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-09DOI: 10.1016/j.actamat.2026.121919
Zhe Li , Liang Wang , Baoxian Su , Qingda Zhang , Jiaxin Du , Zhiwen Li , Chen Liu , Ruirun Chen , Daniel Şopu , Parthiban Ramasamy , Jürgen Eckert , Yanqing Su
The synergistic enhancement of strength and ductility remains an urgently demanded challenge for refractory high entropy alloys (RHEAs). Here, we propose a novel preexisting twinning strategy to achieve excellent strength-ductility synergy. Advanced crystallographic analysis and molecular dynamics simulations reveal that the mechanism of preexisting {112}<111> twinning enhances the ductility via inducing rotational twinning. The rotational twins serve as an effective slip transfer interface and dislocation reaction node, which facilitates the local strain coordination. More crucially, the following rotational twin modes have been identified: {}<>, {}<>, {}<>, {}<> (rotation around the common <110> pole), and a special {}<111> mode, in stark contrast to the classical twinning shear mechanism. At 723-823 K, preexisting twins trigger early dynamic recrystallization, refine grain structures, and serve as nucleation sites for deformation twins, while atomic kinks along the rotational twin boundaries dynamically drive twin rotation and suppress crack propagation. Consequently, the non-equiatomic TiNbZrHfTa alloy reaches a remarkable yield strength of ∼660±11 MPa with 20.74±1.26% elongation at 723 K, and elongations exceeding 17% at 823 K and 50% at 923 K, respectively, which successfully overcomes the intermediate-to-high-temperature embrittlement problem of RHEAs. Altogether, this work offers a transformative pathway for designing high-performance RHEAs for extreme environments.
{"title":"Unveiling superior ductility in refractory high entropy alloy through preexisting {112}<111> twins and novel rotational twinning dynamics","authors":"Zhe Li , Liang Wang , Baoxian Su , Qingda Zhang , Jiaxin Du , Zhiwen Li , Chen Liu , Ruirun Chen , Daniel Şopu , Parthiban Ramasamy , Jürgen Eckert , Yanqing Su","doi":"10.1016/j.actamat.2026.121919","DOIUrl":"10.1016/j.actamat.2026.121919","url":null,"abstract":"<div><div>The synergistic enhancement of strength and ductility remains an urgently demanded challenge for refractory high entropy alloys (RHEAs). Here, we propose a novel preexisting twinning strategy to achieve excellent strength-ductility synergy. Advanced crystallographic analysis and molecular dynamics simulations reveal that the mechanism of preexisting {112}<111> twinning enhances the ductility via inducing rotational twinning. The rotational twins serve as an effective slip transfer interface and dislocation reaction node, which facilitates the local strain coordination. More crucially, the following rotational twin modes have been identified: {<span><math><mrow><mn>1</mn><mover><mn>1</mn><mo>¯</mo></mover><mn>4</mn></mrow></math></span>}<<span><math><mrow><mn>2</mn><mover><mrow><mn>21</mn></mrow><mo>‾</mo></mover></mrow></math></span>>, {<span><math><mrow><mn>1</mn><mover><mn>1</mn><mo>¯</mo></mover><mn>5</mn></mrow></math></span>}<<span><math><mrow><mn>5</mn><mover><mrow><mn>52</mn></mrow><mo>‾</mo></mover></mrow></math></span>>, {<span><math><mrow><mn>1</mn><mover><mn>1</mn><mo>¯</mo></mover><mn>7</mn></mrow></math></span>}<<span><math><mrow><mn>7</mn><mover><mrow><mn>72</mn></mrow><mo>‾</mo></mover></mrow></math></span>>, {<span><math><mrow><mn>1</mn><mover><mn>1</mn><mo>¯</mo></mover><mn>9</mn></mrow></math></span>}<<span><math><mrow><mn>9</mn><mover><mrow><mn>92</mn></mrow><mo>‾</mo></mover></mrow></math></span>> (rotation around the common <110> pole), and a special {<span><math><mrow><mover><mrow><mn>21</mn></mrow><mo>‾</mo></mover><mn>1</mn></mrow></math></span>}<111> mode, in stark contrast to the classical twinning shear mechanism. At 723-823 K, preexisting twins trigger early dynamic recrystallization, refine grain structures, and serve as nucleation sites for deformation twins, while atomic kinks along the rotational twin boundaries dynamically drive twin rotation and suppress crack propagation. Consequently, the non-equiatomic TiNbZrHfTa alloy reaches a remarkable yield strength of ∼660±11 MPa with 20.74±1.26% elongation at 723 K, and elongations exceeding 17% at 823 K and 50% at 923 K, respectively, which successfully overcomes the intermediate-to-high-temperature embrittlement problem of RHEAs. Altogether, this work offers a transformative pathway for designing high-performance RHEAs for extreme environments.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"306 ","pages":"Article 121919"},"PeriodicalIF":9.3,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145974296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-08DOI: 10.1016/j.actamat.2026.121902
Mohammad Ali Seyed Mahmoud , Dominic Renner , Ali Khosravani , Surya R. Kalidindi
Reliable parameter identification in ductile damage models remains challenging because the salient physics of damage progression are localized to small regions in material responses, and their signatures are often diluted in specimen-level measurements. Here, we propose a sequential Bayesian Inference (BI) framework for the calibration of the Gurson–Tvergaard–Needleman (GTN) model using multimodal experimental data (i.e., the specimen-level force–displacement (F–D) measurements and the spatially resolved digital image correlation (DIC) strain fields). This calibration approach builds on a previously developed two-step BI framework that first establishes a low-computational-cost emulator for a physics-based simulator (here, a finite element model incorporating the GTN material model) and then uses the experimental data to sample posteriors for the material model parameters using the Transitional Markov Chain Monte Carlo (T-MCMC). A central challenge to the successful application of this BI framework to the present problem arises from the high-dimensional representations needed to capture the salient features embedded in the F–D curves and the DIC fields. In this paper, it is demonstrated that Principal Component Analysis (PCA) provides low-dimensional representations that make it possible to apply the BI framework to the problem. Most importantly, it is shown that the sequence in which the BI is applied has a dramatic influence on the results obtained. Specifically, it is observed that applying BI first on F–D curves and subsequently on the DIC fields produces improved estimates of the GTN parameters. Possible causes for these observations are discussed in this paper, using AA6111 aluminum alloy as a case study.
{"title":"Sequential Bayesian Inference of the GTN damage model using multimodal experimental data","authors":"Mohammad Ali Seyed Mahmoud , Dominic Renner , Ali Khosravani , Surya R. Kalidindi","doi":"10.1016/j.actamat.2026.121902","DOIUrl":"10.1016/j.actamat.2026.121902","url":null,"abstract":"<div><div>Reliable parameter identification in ductile damage models remains challenging because the salient physics of damage progression are localized to small regions in material responses, and their signatures are often diluted in specimen-level measurements. Here, we propose a sequential Bayesian Inference (BI) framework for the calibration of the Gurson–Tvergaard–Needleman (GTN) model using multimodal experimental data (i.e., the specimen-level force–displacement (F–D) measurements and the spatially resolved digital image correlation (DIC) strain fields). This calibration approach builds on a previously developed two-step BI framework that first establishes a low-computational-cost emulator for a physics-based simulator (here, a finite element model incorporating the GTN material model) and then uses the experimental data to sample posteriors for the material model parameters using the Transitional Markov Chain Monte Carlo (T-MCMC). A central challenge to the successful application of this BI framework to the present problem arises from the high-dimensional representations needed to capture the salient features embedded in the F–D curves and the DIC fields. In this paper, it is demonstrated that Principal Component Analysis (PCA) provides low-dimensional representations that make it possible to apply the BI framework to the problem. Most importantly, it is shown that the sequence in which the BI is applied has a dramatic influence on the results obtained. Specifically, it is observed that applying BI first on F–D curves and subsequently on the DIC fields produces improved estimates of the GTN parameters. Possible causes for these observations are discussed in this paper, using AA6111 aluminum alloy as a case study.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"306 ","pages":"Article 121902"},"PeriodicalIF":9.3,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145923458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-08DOI: 10.1016/j.actamat.2026.121895
Ertugrul Demir , Saikumaran Ayyapan , Weiyue Zhou , Wande Cairang , Kevin B. Woller , Michael P. Short , Djamel Kaoumi
{"title":"Corrigendum to 'Behavior of Fe-based alloys in a liquid lead-bismuth environment under simultaneous proton irradiation and corrosion'","authors":"Ertugrul Demir , Saikumaran Ayyapan , Weiyue Zhou , Wande Cairang , Kevin B. Woller , Michael P. Short , Djamel Kaoumi","doi":"10.1016/j.actamat.2026.121895","DOIUrl":"10.1016/j.actamat.2026.121895","url":null,"abstract":"","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"305 ","pages":"Article 121895"},"PeriodicalIF":9.3,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145972934","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-07DOI: 10.1016/j.actamat.2026.121907
Xin Wang , Xusheng Yang , Weijiu Huang , Yunchang Xin , Dehong Lu , Xianghui Zhu , Mengdi Li , Yanzheng Guo
The plate–shaped T1 phase serves as the primary strengthening precipitate in the advanced Al–Li alloys, and its spatial distribution is a critical factor affecting alloy performance. In this study, electron backscatter diffraction (EBSD), focused ion beam (FIB), and transmission electron microscopy (TEM) were combined to investigate the spatial distribution of T1 plates in specific crystal orientations. The results revealed that the preferred T1 variants mostly precipitated on the habit plane with the maximum Schmid factor. A modified strengthening model was developed considering the uneven distribution of T1 phase. To verify the accuracy of this model, yield strength tests were performed on a single grain using nanoindentation. The analysis indicated that precipitation strengthening could be substantially overestimated in grains containing preferential T1 variants. This study provides a quantitative and precise evaluation of precipitation strengthening in Al–Cu–Li–Mg–Ag alloys, considering specific crystal orientation and spatial distribution.
{"title":"Quantitative study of precipitation strengthening effects of T1 phase in Al–Cu–Li–Mg–Ag alloy: Role of nonuniform spatial distribution","authors":"Xin Wang , Xusheng Yang , Weijiu Huang , Yunchang Xin , Dehong Lu , Xianghui Zhu , Mengdi Li , Yanzheng Guo","doi":"10.1016/j.actamat.2026.121907","DOIUrl":"10.1016/j.actamat.2026.121907","url":null,"abstract":"<div><div>The plate–shaped T<sub>1</sub> phase serves as the primary strengthening precipitate in the advanced Al–Li alloys, and its spatial distribution is a critical factor affecting alloy performance. In this study, electron backscatter diffraction (EBSD), focused ion beam (FIB), and transmission electron microscopy (TEM) were combined to investigate the spatial distribution of T<sub>1</sub> plates in specific crystal orientations. The results revealed that the preferred T<sub>1</sub> variants mostly precipitated on the habit plane with the maximum Schmid factor. A modified strengthening model was developed considering the uneven distribution of T<sub>1</sub> phase. To verify the accuracy of this model, yield strength tests were performed on a single grain using nanoindentation. The analysis indicated that precipitation strengthening could be substantially overestimated in grains containing preferential T<sub>1</sub> variants. This study provides a quantitative and precise evaluation of precipitation strengthening in Al–Cu–Li–Mg–Ag alloys, considering specific crystal orientation and spatial distribution.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"306 ","pages":"Article 121907"},"PeriodicalIF":9.3,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145919763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-07DOI: 10.1016/j.actamat.2025.121891
J.P. Magnussen , Í. Carneiro , K. Ma , C. Coleman , A. Wisbey , H. Swan , A.J. Knowles
The use of conventional zirconium alloys at temperatures above 400 °C is limited by high temperature strength and creep resistance. This has prevented the consideration of zirconium alloys for fusion and Generation IV fission plant designs operating at 500 °C–1000 °C. The physical metallurgy of zirconium is similar to titanium which has seen alloying advances allowing application temperatures up to 600 °C. Although the oxidation resistance of zirconium-based alloys is expected to be poor, in a water environment, new Generation-IV and fusion reactors are designed to operate using alternative coolants such as liquid metals and molten salts. Therefore, a new class of zirconium alloys in the Zr-Al-Sn-(Si,Cr,V) system, designed by analogy to near- titanium alloys, were synthesised by arc melting and processed in a sequence of homogenisation, hot/cold rolling, recrystallisation, and ageing treatments. Microscopy and diffraction identified a refined fully lath grain structure reinforced by nanoscale lamellar or discrete coherent Zr3Al precipitates, with morphology and crystal structure differing with ageing times. Additionally alloying with Si, Cr, and V respectively leads to Zr2Si, ZrCr2, and ZrV2 incoherent precipitates. Tensile testing revealed a strengthening effect by Al, but with significant changes to ductility on ageing depending on the evolution of Zr3Al. Creep testing showed creep rates orders of magnitude better than conventional Zircaloy-4 and nuclear ferritic/martensitic steels, approaching near- Ti alloys. The present work offers new insights and perspectives into how high-temperature zirconium alloys might be designed to meet the requirements for fusion and Gen-IV fission.
{"title":"High temperature zirconium alloys Zr-Al-Sn-(Si,Cr,V) by near-α titanium analogy","authors":"J.P. Magnussen , Í. Carneiro , K. Ma , C. Coleman , A. Wisbey , H. Swan , A.J. Knowles","doi":"10.1016/j.actamat.2025.121891","DOIUrl":"10.1016/j.actamat.2025.121891","url":null,"abstract":"<div><div>The use of conventional zirconium alloys at temperatures above 400 °C is limited by high temperature strength and creep resistance. This has prevented the consideration of zirconium alloys for fusion and Generation IV fission plant designs operating at 500 °C–1000 °C. The physical metallurgy of zirconium is similar to titanium which has seen alloying advances allowing application temperatures up to 600 °C. Although the oxidation resistance of zirconium-based alloys is expected to be poor, in a water environment, new Generation-IV and fusion reactors are designed to operate using alternative coolants such as liquid metals and molten salts. Therefore, a new class of zirconium alloys in the Zr-Al-Sn-(Si,Cr,V) system, designed by analogy to near-<span><math><mi>α</mi></math></span> titanium alloys, were synthesised by arc melting and processed in a sequence of homogenisation, hot/cold rolling, recrystallisation, and ageing treatments. Microscopy and diffraction identified a refined fully lath grain structure reinforced by nanoscale lamellar or discrete coherent Zr<sub>3</sub>Al precipitates, with morphology and crystal structure differing with ageing times. Additionally alloying with Si, Cr, and V respectively leads to Zr<sub>2</sub>Si, ZrCr<sub>2</sub>, and ZrV<sub>2</sub> incoherent precipitates. Tensile testing revealed a strengthening effect by Al, but with significant changes to ductility on ageing depending on the evolution of Zr<sub>3</sub>Al. Creep testing showed creep rates orders of magnitude better than conventional Zircaloy-4 and nuclear ferritic/martensitic steels, approaching near-<span><math><mi>α</mi></math></span> Ti alloys. The present work offers new insights and perspectives into how high-temperature zirconium alloys might be designed to meet the requirements for fusion and Gen-IV fission.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"306 ","pages":"Article 121891"},"PeriodicalIF":9.3,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145919766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-06DOI: 10.1016/j.actamat.2026.121906
Nikita Polin, Shangbin Shen, Fernando Maccari, Alex Aubert, Esmaeil Adabifiroozjaei, Tatiana Smoliarova, Yangyiwei Yang, Xinren Chen, Yurii Skourski, Alaukik Saxena, András Kovács, Rafal E. Dunin-Borkowski, Michael Farle, Bai-Xiang Xu, Leopoldo Molina-Luna, Oliver Gutfleisch, Baptiste Gault, Konstantin Skokov
Permanent magnets containing rare earth elements are essential components for the electrification of society. Ce(Co1-xCux)5 permanent magnets are a model system known for their substantial coercivity, yet the underlying mechanism remains unclear. Here, we investigate Ce(Co0.8Cu0.2)5.4 magnets with a coercivity of ∼1 T. Using transmission electron microscopy (TEM) and atom probe tomography (APT), we identify a nanoscale cellular structure formed by spinodal decomposition. Cu-poor cylindrical cells (∼5-10 nm in diameter, ∼20 nm long) have a disordered CeCo5-type structure and a composition Ce(Co0.9Cu0.1)5.3. Cu-rich cell boundaries are ∼ 5 nm thick and exhibit a modified CeCo5 structure, with Cu ordered on the Co sites and a composition Ce(Co0.7Cu0.3)5.0. Micromagnetic simulations demonstrate that the intrinsic Cu concentration gradients up to 12 at.% Cu/nm lead to a spatial variation in magnetocrystalline anisotropy and domain wall energy, resulting in effective pinning and high coercivity. Compared to Sm2Co17-type magnets, Ce(Co0.8Cu0.2)5.4 displays a finer-scale variation of conventional pinning with lower structural and chemical contrast in its underlying nanostructure. The identification of nanoscale chemical segregation in nearly single-phase Ce(Co0.8Cu0.2)5.4 magnets provides a microstructural basis for the long-standing phenomenon of "giant intrinsic magnetic hardness" in systems such as SmCo5-xMx, highlighting avenues for designing rare-earth-lean permanent magnets via controlled nanoscale segregation.
{"title":"Direct observation of nanoscale pinning centers in Ce(Co0.8Cu0.2)5.4 permanent magnets","authors":"Nikita Polin, Shangbin Shen, Fernando Maccari, Alex Aubert, Esmaeil Adabifiroozjaei, Tatiana Smoliarova, Yangyiwei Yang, Xinren Chen, Yurii Skourski, Alaukik Saxena, András Kovács, Rafal E. Dunin-Borkowski, Michael Farle, Bai-Xiang Xu, Leopoldo Molina-Luna, Oliver Gutfleisch, Baptiste Gault, Konstantin Skokov","doi":"10.1016/j.actamat.2026.121906","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.121906","url":null,"abstract":"Permanent magnets containing rare earth elements are essential components for the electrification of society. Ce(Co<ce:inf loc=\"post\">1-x</ce:inf>Cu<ce:inf loc=\"post\">x</ce:inf>)<ce:inf loc=\"post\">5</ce:inf> permanent magnets are a model system known for their substantial coercivity, yet the underlying mechanism remains unclear. Here, we investigate Ce(Co<ce:inf loc=\"post\">0.8</ce:inf>Cu<ce:inf loc=\"post\">0.2</ce:inf>)<ce:inf loc=\"post\">5.4</ce:inf> magnets with a coercivity of ∼1 T. Using transmission electron microscopy (TEM) and atom probe tomography (APT), we identify a nanoscale cellular structure formed by spinodal decomposition. Cu-poor cylindrical cells (∼5-10 nm in diameter, ∼20 nm long) have a disordered CeCo<ce:inf loc=\"post\">5</ce:inf>-type structure and a composition Ce(Co<ce:inf loc=\"post\">0.9</ce:inf>Cu<ce:inf loc=\"post\">0.1</ce:inf>)<ce:inf loc=\"post\">5.3</ce:inf>. Cu-rich cell boundaries are ∼ 5 nm thick and exhibit a modified CeCo<ce:inf loc=\"post\">5</ce:inf> structure, with Cu ordered on the Co sites and a composition Ce(Co<ce:inf loc=\"post\">0.7</ce:inf>Cu<ce:inf loc=\"post\">0.3</ce:inf>)<ce:inf loc=\"post\">5.0</ce:inf>. Micromagnetic simulations demonstrate that the intrinsic Cu concentration gradients up to 12 at.% Cu/nm lead to a spatial variation in magnetocrystalline anisotropy and domain wall energy, resulting in effective pinning and high coercivity. Compared to Sm<ce:inf loc=\"post\">2</ce:inf>Co<ce:inf loc=\"post\">17</ce:inf>-type magnets, Ce(Co<ce:inf loc=\"post\">0.8</ce:inf>Cu<ce:inf loc=\"post\">0.2</ce:inf>)<ce:inf loc=\"post\">5.4</ce:inf> displays a finer-scale variation of conventional pinning with lower structural and chemical contrast in its underlying nanostructure. The identification of nanoscale chemical segregation in nearly single-phase Ce(Co<ce:inf loc=\"post\">0.8</ce:inf>Cu<ce:inf loc=\"post\">0.2</ce:inf>)<ce:inf loc=\"post\">5.4</ce:inf> magnets provides a microstructural basis for the long-standing phenomenon of \"giant intrinsic magnetic hardness\" in systems such as SmCo<ce:inf loc=\"post\">5-x</ce:inf>M<ce:inf loc=\"post\">x</ce:inf>, highlighting avenues for designing rare-earth-lean permanent magnets via controlled nanoscale segregation.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"44 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2026-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145919764","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-06DOI: 10.1016/j.actamat.2025.121890
Mohammad Hadi Yazdani , Aoyan Liang , Ashley J. Maldonado Otero , Yi Liu , Diana Farkas , Andrea M. Hodge , Timothy J. Rupert , Irene J. Beyerlein , Paulo S. Branicio
In this study, molecular dynamics (MD) simulations are combined with magnetron co-sputtering experiments to examine how Ni-Fe and Ni-Cr compositions affect defect energetics and twin microstructure in thin films. These simulations represent the first direct modeling of nanotwin formation during atomistic thin film deposition. Ensemble MD simulations reveal substantial stochastic variability in grain structure and twin development across deposition runs, yet clear compositional trends emerge. Cr-rich Ni-Cr alloys form dense twin networks with narrow spacing, while Fe-rich Ni-Fe alloys exhibit fewer twins with significantly larger spacing. Scanning transmission electron microscopy (STEM) of Ni-Cr films confirms the predicted high twin density and reduced spacing, validating the link between alloy composition and growth twin formation. Notably, both simulations and experiments reveal that the distribution of twin boundary spacings is log-normal, reflecting the stochastic nature of twin nucleation during deposition. Composition-dependent maps from MD simulations further demonstrate that small variations in Ni-Cr and Ni-Fe chemistry can systematically tune twin boundary formation and enable the design of nanoscale twin architectures. This integrated computational-experimental study establishes a clear inverse relationship between stacking fault energy and average twin spacing, offering a pathway for engineering nanostructured coatings with tailored twin networks and enhanced properties.
{"title":"Composition-driven nanotwin engineering in sputtered Ni-Fe and Ni-Cr films: linking fault energetics to twin thickness","authors":"Mohammad Hadi Yazdani , Aoyan Liang , Ashley J. Maldonado Otero , Yi Liu , Diana Farkas , Andrea M. Hodge , Timothy J. Rupert , Irene J. Beyerlein , Paulo S. Branicio","doi":"10.1016/j.actamat.2025.121890","DOIUrl":"10.1016/j.actamat.2025.121890","url":null,"abstract":"<div><div>In this study, molecular dynamics (MD) simulations are combined with magnetron co-sputtering experiments to examine how Ni-Fe and Ni-Cr compositions affect defect energetics and twin microstructure in thin films. These simulations represent the first direct modeling of nanotwin formation during atomistic thin film deposition. Ensemble MD simulations reveal substantial stochastic variability in grain structure and twin development across deposition runs, yet clear compositional trends emerge. Cr-rich Ni-Cr alloys form dense twin networks with narrow spacing, while Fe-rich Ni-Fe alloys exhibit fewer twins with significantly larger spacing. Scanning transmission electron microscopy (STEM) of Ni-Cr films confirms the predicted high twin density and reduced spacing, validating the link between alloy composition and growth twin formation. Notably, both simulations and experiments reveal that the distribution of twin boundary spacings is log-normal, reflecting the stochastic nature of twin nucleation during deposition. Composition-dependent maps from MD simulations further demonstrate that small variations in Ni-Cr and Ni-Fe chemistry can systematically tune twin boundary formation and enable the design of nanoscale twin architectures. This integrated computational-experimental study establishes a clear inverse relationship between stacking fault energy and average twin spacing, offering a pathway for engineering nanostructured coatings with tailored twin networks and enhanced properties.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"306 ","pages":"Article 121890"},"PeriodicalIF":9.3,"publicationDate":"2026-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145902588","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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