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Facile synthesis of CeO2 nanoparticles through plasma-liquid interaction
IF 3 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2025-02-07 DOI: 10.1016/j.mtla.2025.102367
R. Basumatary , P. Kalita , H. Bailung , R. Brahma
In this study, a facile and energy-efficient technique known as plasma-liquid interaction is employed for crystal growth, defect engineering, and band gap tuning. Using this novel procedure that minimizes the use of chemicals, cubic fluorite CeO2 nanoparticles are produced. The cubic fluorite structure of the prepared nanoparticles is confirmed by the Rietveld refinement method of XRD patterns. The further crystallization of cubic CeO2 nanoparticles (CeO2@300) is observed due to heat treatment following plasma interactions. However, prolonged plasma treatment led to the formation of crystallinity with the generation of oxygen-related vacancies in the host lattice. Post-heat treatment of the materials resulted in increased crystallinity and reduction in vacancies within the host matrix, as confirmed by the vacancy concentration calculations derived from XRD data and the variations of Raman absorption band intensity at 1047.24 cm−1. X-ray photoelectron spectroscopy analysis of the CeO2@RT sample reveals the presence of the Ce3+ ions, indicating the existence of vacancies. TEM analysis showed a good agreement with XRD analysis, revealing a polycrystalline in nature with the particle size distribution ranging from 3 nm to 10 nm. The calculated vacancy concentration indicated a higher vacancy concentration in the CeO2@RT sample, which is further confirmed by Raman spectral analysis. The characteristic vibrations of the Ce-O functional groups are identified using FTIR at absorption bands ranging from 814 cm−1 to 530 cm−1, supporting the cubic fluorite structure of the CeO2 nanoparticles. The band gap energy and defect energy, calculated from the UV–vis spectrum, reveal a lower band gap energy with higher defect energy for CeO2@RT sample, and higher band gap energy with lower defect energy for CeO2@300, making these material suitable for optoelectronic devices.
{"title":"Facile synthesis of CeO2 nanoparticles through plasma-liquid interaction","authors":"R. Basumatary ,&nbsp;P. Kalita ,&nbsp;H. Bailung ,&nbsp;R. Brahma","doi":"10.1016/j.mtla.2025.102367","DOIUrl":"10.1016/j.mtla.2025.102367","url":null,"abstract":"<div><div>In this study, a facile and energy-efficient technique known as plasma-liquid interaction is employed for crystal growth, defect engineering, and band gap tuning. Using this novel procedure that minimizes the use of chemicals, cubic fluorite CeO<sub>2</sub> nanoparticles are produced. The cubic fluorite structure of the prepared nanoparticles is confirmed by the Rietveld refinement method of XRD patterns. The further crystallization of cubic CeO<sub>2</sub> nanoparticles (CeO<sub>2</sub>@300) is observed due to heat treatment following plasma interactions. However, prolonged plasma treatment led to the formation of crystallinity with the generation of oxygen-related vacancies in the host lattice. Post-heat treatment of the materials resulted in increased crystallinity and reduction in vacancies within the host matrix, as confirmed by the vacancy concentration calculations derived from XRD data and the variations of Raman absorption band intensity at 1047.24 cm<sup>−1</sup>. X-ray photoelectron spectroscopy analysis of the CeO<sub>2</sub>@RT sample reveals the presence of the Ce<sup>3+</sup> ions, indicating the existence of vacancies. TEM analysis showed a good agreement with XRD analysis, revealing a polycrystalline in nature with the particle size distribution ranging from 3 nm to 10 nm. The calculated vacancy concentration indicated a higher vacancy concentration in the CeO<sub>2</sub>@RT sample, which is further confirmed by Raman spectral analysis. The characteristic vibrations of the Ce-O functional groups are identified using FTIR at absorption bands ranging from 814 cm<sup>−1</sup> to 530 cm<sup>−1</sup>, supporting the cubic fluorite structure of the CeO<sub>2</sub> nanoparticles. The band gap energy and defect energy, calculated from the UV–vis spectrum, reveal a lower band gap energy with higher defect energy for CeO<sub>2</sub>@RT sample, and higher band gap energy with lower defect energy for CeO<sub>2</sub>@300, making these material suitable for optoelectronic devices.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"39 ","pages":"Article 102367"},"PeriodicalIF":3.0,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143419598","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}
引用次数: 0
Effect of repetition passes in the laser surface texturing of AISI 301LN steel on the anticorrosion properties in molten carbonate salts
IF 3 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2025-02-06 DOI: 10.1016/j.mtla.2025.102365
Mohammad Rezayat , Miguel Morales , Esmaeil Ghadiri Zahrani , Mahmoud Moradi , Bahman Azarhoushang , Antonio Mateo
Laser Surface Texturing (LST) has recently emerged as a corrosion mitigation strategy for materials in contact with high-temperature molten salts used in the next-generation Concentrated Solar Power (CSP) technology. Some issues related to the LST parameters, which may affect the corrosion resistance, have not been addressed yet. Therefore, the present work is focused on the effect of laser input density and pass repetitions for improving the corrosion resistance in molten carbonate salts of AISI 301LN stainless steel. The textured surface produced by a nanosecond laser and the oxide scales formed during subsequent corrosion tests in a molten salt mixture of Li2CO3Na2CO3-K2CO3 at 600 °C were analysed by complementary analytical and microscopy techniques. The results showed that the treated-surface samples at high laser power presented a strong decrease in corrosion rate, as compared with the as-received sample. This is attributed to the formation of a thicker and denser protective oxide scale. However, high laser power increased the susceptibility to corrosion at the heat-affected zone (HAZ). It could be effectively prevented with the accumulation of laser repetition passes, offering a new potential approach to maximize the enhancement of corrosion resistance using LST in the design of components for next-generation CSP plants.
{"title":"Effect of repetition passes in the laser surface texturing of AISI 301LN steel on the anticorrosion properties in molten carbonate salts","authors":"Mohammad Rezayat ,&nbsp;Miguel Morales ,&nbsp;Esmaeil Ghadiri Zahrani ,&nbsp;Mahmoud Moradi ,&nbsp;Bahman Azarhoushang ,&nbsp;Antonio Mateo","doi":"10.1016/j.mtla.2025.102365","DOIUrl":"10.1016/j.mtla.2025.102365","url":null,"abstract":"<div><div>Laser Surface Texturing (LST) has recently emerged as a corrosion mitigation strategy for materials in contact with high-temperature molten salts used in the next-generation Concentrated Solar Power (CSP) technology. Some issues related to the LST parameters, which may affect the corrosion resistance, have not been addressed yet. Therefore, the present work is focused on the effect of laser input density and pass repetitions for improving the corrosion resistance in molten carbonate salts of AISI 301LN stainless steel. The textured surface produced by a nanosecond laser and the oxide scales formed during subsequent corrosion tests in a molten salt mixture of Li<sub>2</sub>CO<sub>3<img></sub>Na<sub>2</sub>CO<sub>3</sub>-K<sub>2</sub>CO<sub>3</sub> at 600 °C were analysed by complementary analytical and microscopy techniques. The results showed that the treated-surface samples at high laser power presented a strong decrease in corrosion rate, as compared with the as-received sample. This is attributed to the formation of a thicker and denser protective oxide scale. However, high laser power increased the susceptibility to corrosion at the heat-affected zone (HAZ). It could be effectively prevented with the accumulation of laser repetition passes, offering a new potential approach to maximize the enhancement of corrosion resistance using LST in the design of components for next-generation CSP plants.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"39 ","pages":"Article 102365"},"PeriodicalIF":3.0,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143350762","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}
引用次数: 0
In situ CLSM observation of Austenite microstructural evolution during hot deformation
IF 3 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2025-02-05 DOI: 10.1016/j.mtla.2025.102355
Abhishek Arya, Muhammad Nabeel, A.B. Phillion
In-situ observations of microstructure evolution during the thermomechanical processing of low-carbon steel have been carried out using a high-temperature tensile testing system (HiTTS) integrated with a confocal laser scanning microscope (CLSM). Experiments were conducted within the temperature range between 800 to 1200 °C, and employing a strain rate of 0.001 s−1 to analyze the evolution of austenite microstructure at different temperatures and to identify the deformation and restoration mechanisms. The findings suggest that at temperatures below 900 °C, planar slip is the dominant deformation mechanism, and slip transfer is more favorable at twin boundaries than at grain boundaries. On the other hand, dynamic recrystallization (DRX) is identified as the primary restoration mechanism above 900 °C. The study identifies various nucleation sites for DRX grains, with triple junctions and grain boundaries serving as the nucleation sites at 900 °C. As the temperature increases to 1000 °C and above, new nucleation sites, such as inside annealing twin boundaries and free twin ends, are observed. The microstructure results suggest that the morphology of the twin boundary changes and loses its character during deformation. The role of annealing twin boundaries on DRX and bulging mechanisms associated with the various nucleation sites are discussed in great detail. Finally, the operational details, including temperature variations along the gauge length and thermal profile adjustments, including overshooting and undershooting and high-temperature surface reactions such as oxidation, decarburization, and evaporation, are meticulously examined.
{"title":"In situ CLSM observation of Austenite microstructural evolution during hot deformation","authors":"Abhishek Arya,&nbsp;Muhammad Nabeel,&nbsp;A.B. Phillion","doi":"10.1016/j.mtla.2025.102355","DOIUrl":"10.1016/j.mtla.2025.102355","url":null,"abstract":"<div><div>In-situ observations of microstructure evolution during the thermomechanical processing of low-carbon steel have been carried out using a high-temperature tensile testing system (HiTTS) integrated with a confocal laser scanning microscope (CLSM). Experiments were conducted within the temperature range between 800 to 1200 °C, and employing a strain rate of 0.001<!--> <!-->s<sup>−1</sup> to analyze the evolution of austenite microstructure at different temperatures and to identify the deformation and restoration mechanisms. The findings suggest that at temperatures below 900 °C, planar slip is the dominant deformation mechanism, and slip transfer is more favorable at twin boundaries than at grain boundaries. On the other hand, dynamic recrystallization (DRX) is identified as the primary restoration mechanism above 900 °C. The study identifies various nucleation sites for DRX grains, with triple junctions and grain boundaries serving as the nucleation sites at 900 °C. As the temperature increases to 1000 °C and above, new nucleation sites, such as inside annealing twin boundaries and free twin ends, are observed. The microstructure results suggest that the morphology of the twin boundary changes and loses its character during deformation. The role of annealing twin boundaries on DRX and bulging mechanisms associated with the various nucleation sites are discussed in great detail. Finally, the operational details, including temperature variations along the gauge length and thermal profile adjustments, including overshooting and undershooting and high-temperature surface reactions such as oxidation, decarburization, and evaporation, are meticulously examined.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"39 ","pages":"Article 102355"},"PeriodicalIF":3.0,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143350760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Mechanisms for pore evolution and heterogeneity in laser powder bed fusion aluminum elucidated through x-ray microscopy
IF 3 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2025-02-04 DOI: 10.1016/j.mtla.2025.102358
Daniel R. Sinclair, Nikhilesh Chawla
Laser powder bed fusion (LPBF) of metallic components produces a unique combination of thermomechanical phenomena such as convection, vaporization, and keyholing. The resulting melt pool structure is not easily characterized in post-facto analysis of printed parts, making process-structure correlations very difficult. Here, structures produced by laser keyhole formation during LPBF of an aerospace aluminum alloy were studied through a simplified sample geometry and controlled remelting. The final distribution of pores within the solidified wall were imaged and quantified through high resolution x-ray microscopy and correlated to the remelted melt pool structure. Based on observations from this multimodal, quantitative analysis, a mechanism for the distribution of porosity is proposed. Novel effects of laser processing conditions on microstructures are thus described, highlighting a key source of heterogeneity across the scales of melt pools to thin 3D features.
{"title":"Mechanisms for pore evolution and heterogeneity in laser powder bed fusion aluminum elucidated through x-ray microscopy","authors":"Daniel R. Sinclair,&nbsp;Nikhilesh Chawla","doi":"10.1016/j.mtla.2025.102358","DOIUrl":"10.1016/j.mtla.2025.102358","url":null,"abstract":"<div><div>Laser powder bed fusion (LPBF) of metallic components produces a unique combination of thermomechanical phenomena such as convection, vaporization, and keyholing. The resulting melt pool structure is not easily characterized in post-facto analysis of printed parts, making process-structure correlations very difficult. Here, structures produced by laser keyhole formation during LPBF of an aerospace aluminum alloy were studied through a simplified sample geometry and controlled remelting. The final distribution of pores within the solidified wall were imaged and quantified through high resolution x-ray microscopy and correlated to the remelted melt pool structure. Based on observations from this multimodal, quantitative analysis, a mechanism for the distribution of porosity is proposed. Novel effects of laser processing conditions on microstructures are thus described, highlighting a key source of heterogeneity across the scales of melt pools to thin 3D features.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"39 ","pages":"Article 102358"},"PeriodicalIF":3.0,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143313273","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}
引用次数: 0
Phase transformation and austenite stability during thermomechanical processing of high (∼5%) Al added low-density medium Mn steel
IF 3 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2025-02-04 DOI: 10.1016/j.mtla.2025.102360
Mukesh Kumar Yadav, Deepak Kumar, Navanit Kumar, Tapas Kumar Bandyopadhyay
In this study, a high Al added low-density medium Mn steel has been developed by conventional melting casting route in an open-air induction furnace, followed by hot forging and hot rolling in the temperature range of 1050-800°C. Finally, it has been intercritically annealed at 750°C for 5, 30, 60, 120, and 180 minutes. The microstructural analysis shows the presence of dual-phase microstructure of delta ferrite and austenite in cast as well as hot forged specimens. While some of the austenite has been transformed to martensite (lenticular shape) in rolled specimen due to a higher cooling rate (water quenching) immediately after hot rolling. After 5 minutes of annealing, needle shape of reverted austenite and intercritical ferrite forms from martensite. As the annealing time increases to 30 minutes, the reverted austenite coalesces and undergoes further transformation into ferrite. This results in the formation of reverted austenite with needle and globular morphologies at 60 minutes of annealing. This annealing condition reveals the optimum mechanical stability due to its morphology and chemical composition, resulting in enhanced TRIP effect as compared to other annealing conditions. Further increase in annealing time to 120 and 180 minutes, volume fraction of reverted austenite decreases significantly due to more dissolution of reverted austenite to intercritical ferrite, leading to reduced TRIP effect. Specimen annealed for 60 minutes, possessing optimal mechanical stability of austenite, exhibits tensile properties with an ultimate tensile stress of 658.45±6 MPa and total elongation of 12±0.95 %, attributed to enhanced TRIP effect.
{"title":"Phase transformation and austenite stability during thermomechanical processing of high (∼5%) Al added low-density medium Mn steel","authors":"Mukesh Kumar Yadav,&nbsp;Deepak Kumar,&nbsp;Navanit Kumar,&nbsp;Tapas Kumar Bandyopadhyay","doi":"10.1016/j.mtla.2025.102360","DOIUrl":"10.1016/j.mtla.2025.102360","url":null,"abstract":"<div><div>In this study, a high Al added low-density medium Mn steel has been developed by conventional melting casting route in an open-air induction furnace, followed by hot forging and hot rolling in the temperature range of 1050-800°C. Finally, it has been intercritically annealed at 750°C for 5, 30, 60, 120, and 180 minutes. The microstructural analysis shows the presence of dual-phase microstructure of delta ferrite and austenite in cast as well as hot forged specimens. While some of the austenite has been transformed to martensite (lenticular shape) in rolled specimen due to a higher cooling rate (water quenching) immediately after hot rolling. After 5 minutes of annealing, needle shape of reverted austenite and intercritical ferrite forms from martensite. As the annealing time increases to 30 minutes, the reverted austenite coalesces and undergoes further transformation into ferrite. This results in the formation of reverted austenite with needle and globular morphologies at 60 minutes of annealing. This annealing condition reveals the optimum mechanical stability due to its morphology and chemical composition, resulting in enhanced TRIP effect as compared to other annealing conditions. Further increase in annealing time to 120 and 180 minutes, volume fraction of reverted austenite decreases significantly due to more dissolution of reverted austenite to intercritical ferrite, leading to reduced TRIP effect. Specimen annealed for 60 minutes, possessing optimal mechanical stability of austenite, exhibits tensile properties with an ultimate tensile stress of 658.45±6 MPa and total elongation of 12±0.95 %, attributed to enhanced TRIP effect.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"39 ","pages":"Article 102360"},"PeriodicalIF":3.0,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143350755","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}
引用次数: 0
Extrusion compression molded critical rare earth free bonded permanent magnets
IF 3 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2025-02-04 DOI: 10.1016/j.mtla.2025.102359
Mariappan Parans Paranthaman , Harshida Parmar , Kaustubh Mungale , James W. Kemp , Haobo Wang , Ikenna C. Nlebedim , Uday Kumar Vaidya
Samarium iron nitride (Sm-Fe-N) bonded magnets have emerged as promising candidates for various industrial applications due to their exceptional magnetic properties. Compounds with magnetic material 95 wt fraction (wt.%) (∼74 vol%) and 97 wt.% (∼81 vol%) of SmFeN in a polyamide (PA12) polymer binder are manufactured using a batch mixer followed by compression molding. A maximum energy product (BH)max of 186.21 kJ.m-3 (23.4 MGOe) is achieved in the 95 wt.% bonded magnets; 97 wt.% magnets had a (BH)max of 165.52 kJ.m-3 (20.8 MGOe). It is found that the degree of alignment (DoA) of 99 % is achieved in the 95 wt.% magnets, whereas the 97 wt.% magnets are limited to a DoA of 90 % respectively. The high DoA can be attributed to low particle-particle interaction during the post-magnetic field alignment process. This research provides a useful insight of binder-particle interactions at very high magnet weight fractions and their effect on magnetic strength and performance.
{"title":"Extrusion compression molded critical rare earth free bonded permanent magnets","authors":"Mariappan Parans Paranthaman ,&nbsp;Harshida Parmar ,&nbsp;Kaustubh Mungale ,&nbsp;James W. Kemp ,&nbsp;Haobo Wang ,&nbsp;Ikenna C. Nlebedim ,&nbsp;Uday Kumar Vaidya","doi":"10.1016/j.mtla.2025.102359","DOIUrl":"10.1016/j.mtla.2025.102359","url":null,"abstract":"<div><div>Samarium iron nitride (Sm-Fe-N) bonded magnets have emerged as promising candidates for various industrial applications due to their exceptional magnetic properties. Compounds with magnetic material 95 wt fraction (wt.%) (∼74 vol%) and 97 wt.% (∼81 vol%) of SmFeN in a polyamide (PA12) polymer binder are manufactured using a batch mixer followed by compression molding. A maximum energy product <em>(BH)</em><sub>max</sub> of 186.21 kJ.m<sup>-3</sup> (23.4 MGOe) is achieved in the 95 wt.% bonded magnets; 97 wt.% magnets had a <em>(BH)</em><sub>max</sub> of 165.52 kJ.m<sup>-3</sup> (20.8 MGOe). It is found that the degree of alignment (DoA) of 99 % is achieved in the 95 wt.% magnets, whereas the 97 wt.% magnets are limited to a DoA of 90 % respectively. The high DoA can be attributed to low particle-particle interaction during the post-magnetic field alignment process. This research provides a useful insight of binder-particle interactions at very high magnet weight fractions and their effect on magnetic strength and performance.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"39 ","pages":"Article 102359"},"PeriodicalIF":3.0,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143350753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Effect of initial grain size on dynamic recrystallization of ultra-large nuclear rotor steel 25Cr2Ni4MoV
IF 3 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2025-02-04 DOI: 10.1016/j.mtla.2025.102362
Xina Huang , Sirui Guo , Wenjing Chen
The effects of different initial grain sizes on dynamic recrystallization (DRX) of ultra-large nuclear rotor steel 25Cr2Ni4MoV based on the isothermal hot-compression tests under different deformation conditions were systematically investigated. The results show that the strain rate is faster, the smaller the initial grain size, the easier DRX occurs. The average grain size of DRX is positively correlated with deformation temperature, negatively correlated with strain rate, and positively correlated with initial grain size. At higher strain rates, the initial grain size has less effect on the average grain size of DRX. However, the degree of DRX is higher in the specimen with a smaller initial grain size. The DRX model was constructed of 25Cr2Ni4MoV with initial grain sizes of 33μm, 179μm, and 1577 μm based on the experimental data. The DRX average grain size models have good fitting accuracy, and the DRX percentage models are consistent with the DRX degree shown by the flow stress strain curves. when DRX occurs sufficiently and the strain rate is low, the larger the initial grain size is, the smaller the critical strain of DRX is, and the easier it is for DRX to occur.
{"title":"Effect of initial grain size on dynamic recrystallization of ultra-large nuclear rotor steel 25Cr2Ni4MoV","authors":"Xina Huang ,&nbsp;Sirui Guo ,&nbsp;Wenjing Chen","doi":"10.1016/j.mtla.2025.102362","DOIUrl":"10.1016/j.mtla.2025.102362","url":null,"abstract":"<div><div>The effects of different initial grain sizes on dynamic recrystallization (DRX) of ultra-large nuclear rotor steel 25Cr2Ni4MoV based on the isothermal hot-compression tests under different deformation conditions were systematically investigated. The results show that the strain rate is faster, the smaller the initial grain size, the easier DRX occurs. The average grain size of DRX is positively correlated with deformation temperature, negatively correlated with strain rate, and positively correlated with initial grain size. At higher strain rates, the initial grain size has less effect on the average grain size of DRX. However, the degree of DRX is higher in the specimen with a smaller initial grain size. The DRX model was constructed of 25Cr2Ni4MoV with initial grain sizes of 33μm, 179μm, and 1577 μm based on the experimental data. The DRX average grain size models have good fitting accuracy, and the DRX percentage models are consistent with the DRX degree shown by the flow stress strain curves. when DRX occurs sufficiently and the strain rate is low, the larger the initial grain size is, the smaller the critical strain of DRX is, and the easier it is for DRX to occur.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"39 ","pages":"Article 102362"},"PeriodicalIF":3.0,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143387814","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}
引用次数: 0
Statically recrystallized grain size as a function of prior stored energy level in the A-286 Fe-based superalloy
IF 3 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2025-02-04 DOI: 10.1016/j.mtla.2025.102361
A. Potenciano , A. Nicolay , A. Da Fonseca Alvarenga , O. Danylova , J. Dairon , M. Bernacki , B. Flipon , N. Bozzolo
A-286 alloy is a Fe-based superalloy used in various engines and gas turbine components. During manufacturing, this alloy is submitted to a solution heat treatment that provides good formability for the subsequent deformation steps. Hence, a good control of grain size evolution is required to avoid the formation of a broad grain size distribution or the growth of abnormally large grains. In this work, a well-controlled strain gradient has been generated by means of indentation tests at room temperature. A specific strain level, calculated by finite element simulations, and the associated dislocation density estimated by the EBSD technique, lead to the activation of selective grain growth during heat treatment after a given incubation time. This study on cold-deformed A-286 alloy allowed a quantitative assessment of recrystallized grain size dependence on stored energy and the identification of the critical stored energy value for grain nucleation, providing a better understanding of A-286 static recrystallization behavior.
{"title":"Statically recrystallized grain size as a function of prior stored energy level in the A-286 Fe-based superalloy","authors":"A. Potenciano ,&nbsp;A. Nicolay ,&nbsp;A. Da Fonseca Alvarenga ,&nbsp;O. Danylova ,&nbsp;J. Dairon ,&nbsp;M. Bernacki ,&nbsp;B. Flipon ,&nbsp;N. Bozzolo","doi":"10.1016/j.mtla.2025.102361","DOIUrl":"10.1016/j.mtla.2025.102361","url":null,"abstract":"<div><div>A-286 alloy is a Fe-based superalloy used in various engines and gas turbine components. During manufacturing, this alloy is submitted to a solution heat treatment that provides good formability for the subsequent deformation steps. Hence, a good control of grain size evolution is required to avoid the formation of a broad grain size distribution or the growth of abnormally large grains. In this work, a well-controlled strain gradient has been generated by means of indentation tests at room temperature. A specific strain level, calculated by finite element simulations, and the associated dislocation density estimated by the EBSD technique, lead to the activation of selective grain growth during heat treatment after a given incubation time. This study on cold-deformed A-286 alloy allowed a quantitative assessment of recrystallized grain size dependence on stored energy and the identification of the critical stored energy value for grain nucleation, providing a better understanding of A-286 static recrystallization behavior.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"39 ","pages":"Article 102361"},"PeriodicalIF":3.0,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143378857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Dissociative adsorption of in-situ grown NiBi with oxygen enabling lower friction and wear of nickel-based composite coating at elevated temperature
IF 3 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2025-02-04 DOI: 10.1016/j.mtla.2025.102364
Huwei Sun , Zaixiu Yang , Shanhong Wan , Gewen Yi , Peiying Shi , Sang The Pham , Anh Kiet Tieu , Benbin Xin , Juanjuan Chen , Wenzhen Wang , Yu Shan , Junyang Wang
Ni-based alloy coatings are increasingly being used in many high-temperature mechanical systems, although they may not necessarily achieve good friction and wear. This study introduces an innovative approach for delivering self-lubricating capability to Ni-based coatings by combining atmospheric plasma spraying (APS) and hot isostatic pressing (HIP). We demonstrate that HIP improves the densification, hardness, and adhesive strength of the coatings while offering outstanding friction reduction and wear resistance at 400 °C. This superior performance is attributed to the dissociative adsorption of in-situ NiBi compounds with oxygen, which results in the formation of BiNiO3 and NiO during friction. These compounds are key to the mitigation of interfacial adhesion and the formation of low-shear oxide tribolayers. This study provides a new method for preparing low-friction and anti-wear Ni-based coatings and outlines the chemical design rules for their self-lubricating properties through surface microstructural characterizations and atomic calculations.
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引用次数: 0
The evolution of microscopic damage mechanisms during actuation fatigue cycling in high temperature shape memory alloys
IF 3 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2025-02-03 DOI: 10.1016/j.mtla.2025.102356
Faith Gantz , Alexander Demblon , Ibrahim Karaman , Marcus L. Young
Shape memory alloys (SMAs) offer an alternative lightweight and compact option to conventional actuators as solid-state actuators due to their high energy density. Before commercial use in the automotive or aerospace industries can be realized, the durability and functionality of high temperature SMAs (HTSMAs), with operating temperatures exceeding 100 °C, need to be characterized by examining the actuation fatigue properties. Macroscopic evaluation has been well-documented, but to further improve the thermomechanical response and actuation fatigue then the governing microscopic damage mechanisms need to be identified. With this motivation, the effects of upper cycle temperature (UCT) levels on actuation fatigue properties of a Ni-rich Ni50.3Ti29.7Hf20 HTSMA were investigated in combination with high energy synchrotron radiation X-ray diffraction (SR-XRD) experiments. Fatigue tests were performed to compare three UCT levels above austenite finish (Af) temperature under a constant load of 300 MPa and SR-XRD was used to determine the residual micro-strains associated with accumulated strain. Overheating much greater than the Af (in this case, >100 °C) transformation temperature leads to oxidation and slip deformation associated with grain growth. Whereas operating at temperatures slightly above Af (<100 °C) was shown to extend fatigue life by preferring twinning deformation. Existing defects and high strain rate conditions will cause actuation strain degradation as a consequence of multiple transformation fronts accumulating stress concentrators at these initiation sites. Lower UCT allows damage deformation to propagate slowly across the sample so that deformation is primarily associated with twinning mechanisms before slip for the duration of the fatigue test.
{"title":"The evolution of microscopic damage mechanisms during actuation fatigue cycling in high temperature shape memory alloys","authors":"Faith Gantz ,&nbsp;Alexander Demblon ,&nbsp;Ibrahim Karaman ,&nbsp;Marcus L. Young","doi":"10.1016/j.mtla.2025.102356","DOIUrl":"10.1016/j.mtla.2025.102356","url":null,"abstract":"<div><div>Shape memory alloys (SMAs) offer an alternative lightweight and compact option to conventional actuators as solid-state actuators due to their high energy density. Before commercial use in the automotive or aerospace industries can be realized, the durability and functionality of high temperature SMAs (HTSMAs), with operating temperatures exceeding 100 °C, need to be characterized by examining the actuation fatigue properties. Macroscopic evaluation has been well-documented, but to further improve the thermomechanical response and actuation fatigue then the governing microscopic damage mechanisms need to be identified. With this motivation, the effects of upper cycle temperature (UCT) levels on actuation fatigue properties of a Ni-rich Ni<sub>50.3</sub>Ti<sub>29.7</sub>Hf<sub>20</sub> HTSMA were investigated in combination with high energy synchrotron radiation X-ray diffraction (SR-XRD) experiments. Fatigue tests were performed to compare three UCT levels above austenite finish (A<sub>f</sub>) temperature under a constant load of 300 MPa and SR-XRD was used to determine the residual micro-strains associated with accumulated strain. Overheating much greater than the A<sub>f</sub> (in this case, &gt;100 °C) transformation temperature leads to oxidation and slip deformation associated with grain growth. Whereas operating at temperatures slightly above A<sub>f</sub> (&lt;100 °C) was shown to extend fatigue life by preferring twinning deformation. Existing defects and high strain rate conditions will cause actuation strain degradation as a consequence of multiple transformation fronts accumulating stress concentrators at these initiation sites. Lower UCT allows damage deformation to propagate slowly across the sample so that deformation is primarily associated with twinning mechanisms before slip for the duration of the fatigue test.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"39 ","pages":"Article 102356"},"PeriodicalIF":3.0,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143378856","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}
引用次数: 0
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Materialia
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