Pub Date : 2025-11-19DOI: 10.1016/j.mtla.2025.102613
Achraf Atila , Yasser Bakhouch , Zhuocheng Xie
Oxide glasses have proven to be useful across a wide range of technological applications. Nevertheless, their medium-range structure has remained elusive. Previous studies focused on ring statistics as a metric of the medium-range structure, but this metric provides an incomplete picture of the glassy structure. Here, we use atomistic simulations and state-of-the-art topological analysis tools, namely persistent homology (PH), to analyze the medium-range structure of the archetypal oxide glass (Silica) at ambient temperatures and with varying pressures. PH presents an unbiased definition of loops and voids, providing an advantage over other methods for studying the structure and topology of complex materials, such as glasses, across multiple length scales. We captured subtle topological transitions in medium-range order and cavity distributions, providing new insights into glass structure. Our work provides a robust way for extracting the void distribution of oxide glasses based on PH.
{"title":"Revealing the void-size distribution of silica glass using persistent homology","authors":"Achraf Atila , Yasser Bakhouch , Zhuocheng Xie","doi":"10.1016/j.mtla.2025.102613","DOIUrl":"10.1016/j.mtla.2025.102613","url":null,"abstract":"<div><div>Oxide glasses have proven to be useful across a wide range of technological applications. Nevertheless, their medium-range structure has remained elusive. Previous studies focused on ring statistics as a metric of the medium-range structure, but this metric provides an incomplete picture of the glassy structure. Here, we use atomistic simulations and state-of-the-art topological analysis tools, namely persistent homology (PH), to analyze the medium-range structure of the archetypal oxide glass (Silica) at ambient temperatures and with varying pressures. PH presents an unbiased definition of loops and voids, providing an advantage over other methods for studying the structure and topology of complex materials, such as glasses, across multiple length scales. We captured subtle topological transitions in medium-range order and cavity distributions, providing new insights into glass structure. Our work provides a robust way for extracting the void distribution of oxide glasses based on PH.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"44 ","pages":"Article 102613"},"PeriodicalIF":2.9,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145578547","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-19DOI: 10.1016/j.mtla.2025.102614
Katrine Top Hartmann , Marie Høy Hansen , Anton Alexander Nolte Peterlin , Julie Melsted Birch , Bent Aalbæk , Johanne Gade Lilleøre , Mats Bue , Nicole Lind Henriksen , Ida Thaarup , Thomas Bjarnsholt , Andreas Petersen , Kerstin Skovgaard , Anders Odgaard , Michail Vardavoulias , Konstantinos Giannakopoulos , Michael Arkas , Henrik Elvang Jensen , Louise Kruse Jensen
The risk of infection when inserting orthopedic devices like prostheses, screws, and plates represents a serious and challenging complication in orthopedic surgery. Most infections result from bacterial introduction during surgery, making it crucial and clinically relevant to protect the devices and surrounding tissue with intraoperative antimicrobials, especially in high-risk patients. Therefore, to mitigate this risk, antimicrobial coatings for different types of orthopedic devices have received substantial attention in recent decades with the goal of developing a “self-cleaning” surface. In here, we investigated a new and highly promising coating candidate. The coating was made of a hyperbranched poly(ethylene imine (PEI)) + orthosilicic acid-based hydrogel, that in a sol-gel process was transformed into a solid xerogel, which afterwards was loaded with gentamicin as active compound. The gentamicin-loaded xerogel coating was applied to functional implants i.e., cancellous bone screws, and tested within an advanced minipig model of Staphylococcus aureus induced peri‑prosthetic joint infection, without the use of systemic antimicrobial therapy. The study included evaluation of antimicrobial efficacy (quantification of bacterial load on the screw surface and within the surrounding tissues), pre -and post-insertion characterization of the coating, assessment of local inflammation and gene expression, and acute toxicity. Additionally, the pharmacokinetic in-vivo gentamicin release profile was measured using microdialysis in relevant local compartments. Due to a quick, locally high, and complete gentamicin release, the coating completely eradicated S. aureus from all compartments in all but one minipig. Therefore, this study shows proof of concept for the effectiveness of preventive antimicrobial release-based coatings.
{"title":"Gentamicin-loaded xerogel coating prevents peri‑prosthetic joint infection in an adult Göttingen minipig model","authors":"Katrine Top Hartmann , Marie Høy Hansen , Anton Alexander Nolte Peterlin , Julie Melsted Birch , Bent Aalbæk , Johanne Gade Lilleøre , Mats Bue , Nicole Lind Henriksen , Ida Thaarup , Thomas Bjarnsholt , Andreas Petersen , Kerstin Skovgaard , Anders Odgaard , Michail Vardavoulias , Konstantinos Giannakopoulos , Michael Arkas , Henrik Elvang Jensen , Louise Kruse Jensen","doi":"10.1016/j.mtla.2025.102614","DOIUrl":"10.1016/j.mtla.2025.102614","url":null,"abstract":"<div><div>The risk of infection when inserting orthopedic devices like prostheses, screws, and plates represents a serious and challenging complication in orthopedic surgery. Most infections result from bacterial introduction during surgery, making it crucial and clinically relevant to protect the devices and surrounding tissue with intraoperative antimicrobials, especially in high-risk patients. Therefore, to mitigate this risk, antimicrobial coatings for different types of orthopedic devices have received substantial attention in recent decades with the goal of developing a “self-cleaning” surface. In here, we investigated a new and highly promising coating candidate. The coating was made of a hyperbranched poly(ethylene imine (PEI)) + orthosilicic acid-based hydrogel, that in a sol-gel process was transformed into a solid xerogel, which afterwards was loaded with gentamicin as active compound. The gentamicin-loaded xerogel coating was applied to functional implants i.e., cancellous bone screws, and tested within an advanced minipig model of <em>Staphylococcus aureus</em> induced peri‑prosthetic joint infection, without the use of systemic antimicrobial therapy. The study included evaluation of antimicrobial efficacy (quantification of bacterial load on the screw surface and within the surrounding tissues), pre -and post-insertion characterization of the coating, assessment of local inflammation and gene expression, and acute toxicity. Additionally, the pharmacokinetic in-vivo gentamicin release profile was measured using microdialysis in relevant local compartments. Due to a quick, locally high, and complete gentamicin release, the coating completely eradicated <em>S. aureus</em> from all compartments in all but one minipig. Therefore, this study shows proof of concept for the effectiveness of preventive antimicrobial release-based coatings.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"44 ","pages":"Article 102614"},"PeriodicalIF":2.9,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145578549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-12DOI: 10.1016/j.mtla.2025.102608
N.L. Church, O.G. Reed, G.J. Wise, N.G. Jones
Metastable β Ti-Nb alloys have potential as biomedical implant materials due to a low elastic modulus and good biocompatibility. However, these alloys are susceptible to the ⍵ phase transformation, which significantly stiffens the alloy. Despite this, there is limited agreement within the literature whether the form of the ⍵ phase is important in governing subsequent mechanical response. Here, this work utilises synchrotron X-ray diffraction data to conclusively demonstrates that ⍵iso significantly inhibits a mechanically driven martensitic transformation, whereas ⍵ath is seen to have a much smaller effect. This work therefore has important consequences for the design of new transforming materials.
{"title":"On the role of athermal and isothermal omega on the stress induced martensitic transformation in Ti-18Nb (at.%)","authors":"N.L. Church, O.G. Reed, G.J. Wise, N.G. Jones","doi":"10.1016/j.mtla.2025.102608","DOIUrl":"10.1016/j.mtla.2025.102608","url":null,"abstract":"<div><div>Metastable β Ti-Nb alloys have potential as biomedical implant materials due to a low elastic modulus and good biocompatibility. However, these alloys are susceptible to the ⍵ phase transformation, which significantly stiffens the alloy. Despite this, there is limited agreement within the literature whether the form of the ⍵ phase is important in governing subsequent mechanical response. Here, this work utilises synchrotron X-ray diffraction data to conclusively demonstrates that ⍵<sub>iso</sub> significantly inhibits a mechanically driven martensitic transformation, whereas ⍵<sub>ath</sub> is seen to have a much smaller effect. This work therefore has important consequences for the design of new transforming materials.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"44 ","pages":"Article 102608"},"PeriodicalIF":2.9,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145578548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-12DOI: 10.1016/j.mtla.2025.102603
Changle Li , Christopher A. Schuh
We apply a multiscale quantum mechanics/molecular mechanics (QM/MM) approach to compute the zero-Kelvin segregation energies of 42 solute elements in polycrystalline Cu. High-throughput quantum accurate segregation spectra are established using the projector augmented wave method with a plane-wave basis, enabling direct prediction of solute enrichment as a function of temperature and composition. This in turn opens new opportunities to analyze experimental data and design copper alloys.
{"title":"Multiscale computations of grain boundary solute segregation spectra in Cu polycrystals","authors":"Changle Li , Christopher A. Schuh","doi":"10.1016/j.mtla.2025.102603","DOIUrl":"10.1016/j.mtla.2025.102603","url":null,"abstract":"<div><div>We apply a multiscale quantum mechanics/molecular mechanics (QM/MM) approach to compute the zero-Kelvin segregation energies of 42 solute elements in polycrystalline Cu. High-throughput quantum accurate segregation spectra are established using the projector augmented wave method with a plane-wave basis, enabling direct prediction of solute enrichment as a function of temperature and composition. This in turn opens new opportunities to analyze experimental data and design copper alloys.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"44 ","pages":"Article 102603"},"PeriodicalIF":2.9,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145578544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-10DOI: 10.1016/j.mtla.2025.102605
Bangwei Jin , Yulin Peng , Chen Zou , Dexin Yang , Xuefeng Zhang
Electron–phonon interactions have significant influences on the photoluminescent (PL) emissions and carrier dynamics of the hybrid perovskite CH(NH2)2PbBr3 (FAPbBr3). Here, we investigate these interactions in a FAPbBr3 single crystal using femtosecond laser excitation. Temperature–dependent PL spectra (80–310 K) are analyzed to separate the contributions of acoustic and longitudinal optical (LO) phonons to the PL linewidth. We find that LO phonons dominate the PL linewidth broadening above 80 K. Free and defect–bound exciton binding energies are examined via Arrhenius analysis, revealing that defected–bound excitons have lower binding energy than free excitons. Additionally, temperature–dependent X–ray diffraction and PL measurements reveal a tetragonal–to–orthorhombic phase transition near 180 K and a freezing behavior of the FA+ cations around 150 K. In contrast to the octahedral tilting transition, the freezing of FA+ rotations induces a remarkable shift in PL peak energy and alters exciton–phonon coupling. These findings clarify the intrinsic electron/exciton–phonon interactions in FAPbBr3 single crystals and provide insight for optimizing their optoelectronic performance.
{"title":"Electron/exciton–phonon coupling in FAPbBr3 single crystals","authors":"Bangwei Jin , Yulin Peng , Chen Zou , Dexin Yang , Xuefeng Zhang","doi":"10.1016/j.mtla.2025.102605","DOIUrl":"10.1016/j.mtla.2025.102605","url":null,"abstract":"<div><div>Electron–phonon interactions have significant influences on the photoluminescent (PL) emissions and carrier dynamics of the hybrid perovskite CH(NH<sub>2</sub>)<sub>2</sub>PbBr<sub>3</sub> (FAPbBr<sub>3</sub>). Here, we investigate these interactions in a FAPbBr<sub>3</sub> single crystal using femtosecond laser excitation. Temperature–dependent PL spectra (80–310 K) are analyzed to separate the contributions of acoustic and longitudinal optical (LO) phonons to the PL linewidth. We find that LO phonons dominate the PL linewidth broadening above 80 K. Free and defect–bound exciton binding energies are examined via Arrhenius analysis, revealing that defected–bound excitons have lower binding energy than free excitons. Additionally, temperature–dependent X–ray diffraction and PL measurements reveal a tetragonal–to–orthorhombic phase transition near 180 K and a freezing behavior of the FA<sup>+</sup> cations around 150 K. In contrast to the octahedral tilting transition, the freezing of FA<sup>+</sup> rotations induces a remarkable shift in PL peak energy and alters exciton–phonon coupling. These findings clarify the intrinsic electron/exciton–phonon interactions in FAPbBr<sub>3</sub> single crystals and provide insight for optimizing their optoelectronic performance.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"44 ","pages":"Article 102605"},"PeriodicalIF":2.9,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145525455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-09DOI: 10.1016/j.mtla.2025.102606
Colin McLagan , Todd M. Butler , Adib J. Samin
Impurities at the grain boundary (GB) can result in the weakening of local structures possibly leading to fracture. This work uses first-principle calculations to study the effect of interstitial oxygen (O) on two tungsten (W) symmetric tilt GBs – the Σ3(112) and Σ3(111). Solution energy calculations show that O is thermodynamically driven towards the GB. Migration energy analysis indicates that O must overcome large energy barriers to exit the GB, effectively trapping interstitial O at these sites. The strength of both GBs studied here was found to monotonically decrease with increasing oxygen coverage up to the point of oxide precipitation. This work found that the work of separation of a W Σ3(112) and a W Σ3(111) GB decreased by a factor of two from a pure GB to a W(112)/WO3(001) and W(111)/WO3(001) interface respectively, potentially making these regions the most vulnerable to cracking. Finally, our computations on the initial phase of the oxide growing on a metal substrate demonstrated that the crystalline oxide was thermodynamically more favorable than the amorphous oxide when two or more oxide layers existed. Establishing these structure-property relationships may help provide some insight into engineering improved structural materials.
{"title":"A first-principles investigation of the early-stage oxidation in two Σ3 tungsten grain boundaries","authors":"Colin McLagan , Todd M. Butler , Adib J. Samin","doi":"10.1016/j.mtla.2025.102606","DOIUrl":"10.1016/j.mtla.2025.102606","url":null,"abstract":"<div><div>Impurities at the grain boundary (GB) can result in the weakening of local structures possibly leading to fracture. This work uses first-principle calculations to study the effect of interstitial oxygen (O) on two tungsten (W) symmetric tilt GBs – the Σ3<span><math><mrow><mo>[</mo><mrow><mn>1</mn><mover><mn>1</mn><mo>¯</mo></mover><mn>0</mn></mrow><mo>]</mo></mrow></math></span>(112) and Σ3<span><math><mrow><mo>[</mo><mrow><mn>1</mn><mover><mn>1</mn><mo>¯</mo></mover><mn>0</mn></mrow><mo>]</mo></mrow></math></span>(111). Solution energy calculations show that O is thermodynamically driven towards the GB. Migration energy analysis indicates that O must overcome large energy barriers to exit the GB, effectively trapping interstitial O at these sites. The strength of both GBs studied here was found to monotonically decrease with increasing oxygen coverage up to the point of oxide precipitation. This work found that the work of separation of a W Σ3(112) and a W Σ3(111) GB decreased by a factor of two from a pure GB to a W(112)/WO<sub>3</sub>(001) and W(111)/WO<sub>3</sub>(001) interface respectively, potentially making these regions the most vulnerable to cracking. Finally, our computations on the initial phase of the oxide growing on a metal substrate demonstrated that the crystalline oxide was thermodynamically more favorable than the amorphous oxide when two or more oxide layers existed. Establishing these structure-property relationships may help provide some insight into engineering improved structural materials.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"44 ","pages":"Article 102606"},"PeriodicalIF":2.9,"publicationDate":"2025-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145525457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, we investigate the structural and magnetic properties of epitaxial Fe films grown on SrTiO3 (STO) substrates using molecular beam epitaxy (MBE). High-quality epitaxial Fe films with a body-centered cubic (bcc) structure and well-defined crystallographic orientations were obtained. Remarkably, magnetic characterization measurements revealed abnormal hysteresis loop behaviors, including multi-step magnetization reversal and an unusual opening at both ends of the loops. These anomalies are likely related to strain-induced effects from the STO substrate and interfacial atomic displacements, which may alter spin alignment and exchange interactions in the Fe film, possibly giving rise to a ferrimagnetic-like net. The visualized non-uniform domain dynamics during the magnetization process further suggest such abnormal behaviors. Notably, such features were not observed in Fe films grown on substrates like MgO, GaAs, and Al2O3, indicating the potential role of substrate-induced strain in tailoring the magnetic properties. These findings provide new insights into how substrate strain and interfacial effects might help engineer complex spin structures in magnetic thin films. This work highlights the potential for utilizing strain-engineering to design advanced magnetic materials for spintronics and other magnetic device applications.
{"title":"Strain-induced ferrimagnetism-like in Fe epitaxial films on SrTiO₃: Structure and magnetic properties","authors":"Minh-Anh Nguyen Tran , Kyoung-Woong Moon , Chanyong Hwang","doi":"10.1016/j.mtla.2025.102604","DOIUrl":"10.1016/j.mtla.2025.102604","url":null,"abstract":"<div><div>In this study, we investigate the structural and magnetic properties of epitaxial Fe films grown on SrTiO<sub>3</sub> (STO) substrates using molecular beam epitaxy (MBE). High-quality epitaxial Fe films with a body-centered cubic (bcc) structure and well-defined crystallographic orientations were obtained. Remarkably, magnetic characterization measurements revealed abnormal hysteresis loop behaviors, including multi-step magnetization reversal and an unusual opening at both ends of the loops. These anomalies are likely related to strain-induced effects from the STO substrate and interfacial atomic displacements, which may alter spin alignment and exchange interactions in the Fe film, possibly giving rise to a ferrimagnetic-like net. The visualized non-uniform domain dynamics during the magnetization process further suggest such abnormal behaviors. Notably, such features were not observed in Fe films grown on substrates like MgO, GaAs, and Al<sub>2</sub>O<sub>3</sub>, indicating the potential role of substrate-induced strain in tailoring the magnetic properties. These findings provide new insights into how substrate strain and interfacial effects might help engineer complex spin structures in magnetic thin films. This work highlights the potential for utilizing strain-engineering to design advanced magnetic materials for spintronics and other magnetic device applications.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"44 ","pages":"Article 102604"},"PeriodicalIF":2.9,"publicationDate":"2025-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145525456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-08DOI: 10.1016/j.mtla.2025.102601
Xuening Si , Hailin Zhai , Ziyi Li , Baiming Yao , Xianfeng Ma , Fei Zhu , WeiAn Dang , Weizhong Fan , Zhen Wang
This study investigated the microstructure-dependent plastic deformation and fracture mechanism of Al₀.₆CoCrFeNi dual-phase high-entropy alloy (HEA), with particular focus on the effects of initial dislocation density, grain refinement, and phase distribution. The results revealed that the tensile strength exhibited a gradual decrease with increasing annealing temperature, while both microhardness and grain size of face-centered cubic (FCC) and body-centered cubic (BCC) phases demonstrated non-monotonic evolutionary trends. This phenomenon was attributed to the coupled effects of evolving phase distribution, grain size, and initial dislocation density, together with the phase-specific mechanical responses of FCC and BCC phases. The grain size disparity between FCC and BCC phases critically governed microcrack nucleation pathways: aberrant BCC phase coarsening and interphase hardness mismatch accelerated crack propagation in coarse-grained (CG) specimens, whereas fine-grained (FG) counterparts achieved optimal strength-ductility synergy through synergistic grain refinement of FCC matrix and dispersion strengthening by fine BCC precipitates. A physics-based modification of the Hall-Petch relationship was developed to quantitatively evaluate the contribution of grain size, dislocation density, and phase-specific hardness to the macroscopic mechanical property.
{"title":"Effects of annealed microstructures on the plastic deformation and cracking behavior of Al0.6CoCrFeNi dual-phase high-entropy alloy","authors":"Xuening Si , Hailin Zhai , Ziyi Li , Baiming Yao , Xianfeng Ma , Fei Zhu , WeiAn Dang , Weizhong Fan , Zhen Wang","doi":"10.1016/j.mtla.2025.102601","DOIUrl":"10.1016/j.mtla.2025.102601","url":null,"abstract":"<div><div>This study investigated the microstructure-dependent plastic deformation and fracture mechanism of Al₀.₆CoCrFeNi dual-phase high-entropy alloy (HEA), with particular focus on the effects of initial dislocation density, grain refinement, and phase distribution. The results revealed that the tensile strength exhibited a gradual decrease with increasing annealing temperature, while both microhardness and grain size of face-centered cubic (FCC) and body-centered cubic (BCC) phases demonstrated non-monotonic evolutionary trends. This phenomenon was attributed to the coupled effects of evolving phase distribution, grain size, and initial dislocation density, together with the phase-specific mechanical responses of FCC and BCC phases. The grain size disparity between FCC and BCC phases critically governed microcrack nucleation pathways: aberrant BCC phase coarsening and interphase hardness mismatch accelerated crack propagation in coarse-grained (CG) specimens, whereas fine-grained (FG) counterparts achieved optimal strength-ductility synergy through synergistic grain refinement of FCC matrix and dispersion strengthening by fine BCC precipitates. A physics-based modification of the Hall-Petch relationship was developed to quantitatively evaluate the contribution of grain size, dislocation density, and phase-specific hardness to the macroscopic mechanical property.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"44 ","pages":"Article 102601"},"PeriodicalIF":2.9,"publicationDate":"2025-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145525459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-07DOI: 10.1016/j.mtla.2025.102599
E.C. Galliopoulou , S. He , G.T. Martinez , H. Shang , C. Jones , M. Zimina , J. Siefert , J.D. Parker , G.M. Hughes , A. Cocks , T.L. Martin
Creep cavity formation in Grade 91 steel components is a serious challenge that energy applications face, as cavities grow, coalesce, form propagating cracks and eventually lead to failure. This study investigates the microstructural parameters associated with creep cavity nucleation in ex-service martensitic P91 material. Three uniaxial and one double-notched creep tested samples were investigated, interrupted at 0.5 % and 1 % and failed at 3.7 % strain fractions, in order to inspect the evolution of damage in early and late stages of the creep life. A correlative SEM-EBSD technique was employed, revealing that most cavities nucleated along the parent austenite grain boundary (PAGB) structure, with grain boundary junctions exhibiting increased susceptibility to damage. Although PAGBs with misorientation angles of 15–35° and 60° were not the predominant boundary type in the parent microstructure, they exhibited high cavitation ratios. Manganese sulfide (MnS) inclusions were found to be highly prone to cavity nucleation, while smaller precipitates, such as M23C6 carbides, Laves phase and MX-type nitrides, facilitated cavity formation at the MnS/martensite matrix interface. Since the vast majority of grains were soft, no clear correlation between the Schmid Factor and cavitation could be established.
{"title":"Microstructural parameters associated with cavity nucleation in martensitic Grade 91 steel under creep conditions","authors":"E.C. Galliopoulou , S. He , G.T. Martinez , H. Shang , C. Jones , M. Zimina , J. Siefert , J.D. Parker , G.M. Hughes , A. Cocks , T.L. Martin","doi":"10.1016/j.mtla.2025.102599","DOIUrl":"10.1016/j.mtla.2025.102599","url":null,"abstract":"<div><div>Creep cavity formation in Grade 91 steel components is a serious challenge that energy applications face, as cavities grow, coalesce, form propagating cracks and eventually lead to failure. This study investigates the microstructural parameters associated with creep cavity nucleation in ex-service martensitic P91 material. Three uniaxial and one double-notched creep tested samples were investigated, interrupted at 0.5 % and 1 % and failed at 3.7 % strain fractions, in order to inspect the evolution of damage in early and late stages of the creep life. A correlative SEM-EBSD technique was employed, revealing that most cavities nucleated along the parent austenite grain boundary (PAGB) structure, with grain boundary junctions exhibiting increased susceptibility to damage. Although PAGBs with misorientation angles of 15–35° and 60° were not the predominant boundary type in the parent microstructure, they exhibited high cavitation ratios. Manganese sulfide (MnS) inclusions were found to be highly prone to cavity nucleation, while smaller precipitates, such as M<sub>23</sub>C<sub>6</sub> carbides, Laves phase and MX-type nitrides, facilitated cavity formation at the MnS/martensite matrix interface. Since the vast majority of grains were soft, no clear correlation between the Schmid Factor and cavitation could be established.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"44 ","pages":"Article 102599"},"PeriodicalIF":2.9,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145525453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-07DOI: 10.1016/j.mtla.2025.102602
Chen Cai , Gabriel Spartacus , Amlan Das , Katherine S. Shanks , Wangzhong Mu , Peter Hedström
The parent austenite grain size (PAGS) plays a critical role in governing the austenite to martensite transformation in steels, as it directly influences the stability of the austenite phase. Therefore, a thorough understanding of the PAGS effect is essential for the design of advanced steels with optimized performance. In this study, we investigate the influence of PAGS on both athermal and deformation-induced martensitic transformation (AMT and DIMT) in an Fe-18Cr-12Ni (wt.%) alloy. In situ and ex situ high-energy synchrotron X-ray diffraction (HEXRD) measurements were conducted during tensile loading and after cooling, respectively. These measurements were complemented by electron microscopy to elucidate the underlying mechanisms governing the PAGS effect on martensitic transformation. The results reveal PAGS exerts opposite effects on AMT and DIMT. Grain refinement increases the barrier for martensitic transformation onset, and in the case of AMT, this leads to a lower martensite start temperature (Ms) and suppressed transformation. Conversely, although grain refinement delays DIMT and raises the critical stress required for its initiation, the associated Hall-Petch strengthening enhances the flow stress, thereby promoting DIMT at higher strain levels. These findings offer valuable insights for the microstructural design of austenitic steels and contribute to the modeling of martensitic transformation behavior under varying mechanical and thermal conditions.
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