Pub Date : 2024-09-26DOI: 10.1016/j.jmst.2024.08.062
Xueyuan Qiu, Xiao Han, Baorui Dong, Meng Zong, Runtong Zhou, Teng Zhang, Pan Wang, Chang Guo, Hejun Li, Jianhua Hao
Stimulus-responsive actuators are novel functional devices capable of sensing external stimuli and exhibiting specific deformation responses. MXene, owing to its unique 2D structure and efficient energy conversion efficiency, has bridged the gap in traditional devices and shown great potential for multiple stimulus-responsive actuators. However, the drawbacks of pure MXene films, including susceptibility to oxidation and vulnerability to shear stress, hinder their applications. Through composite modification and structural design strategies, a three-layer structured MXene-carbon nanotubes hybrid film (tHCM) is fabricated, exhibiting a tensile strength and fracture strain of 153.8 MPa and 4.65%, respectively, representing improvements of 598.4% and 226.8% compared to the initial film. Meanwhile, the film maintains excellent stability demonstrating the enhancing effects of hydrogen bonds and densely packed structure. The hybrid films demonstrate unique and facile welding features due to splicing properties, enabling the formation of complex configurations. In terms of electro-/photo-thermal conversion performance, the hybrid film can reach a reasonably high temperature of 250 ℃ at low voltage (2.5 V) and 110.6 ℃ under 150 mW cm–2 infrared light. Leveraging the thermal expansion mismatch between tHCM and thermoplastic films, an integrated, flexible, and weldable actuator with unique electro/photo-response is developed, and various biomimetic driving applications, particularly, the light-mediated hierarchical transmission and precise motion along predetermined trajectory are realized. This work not only provides an effective strategy for modifying MXene composite films but also advances the design of novel actuators, offering broad application prospects in fields such as stimulus-responsive actuated robots and cargo transportation.
{"title":"Multi-stimulus responsive actuator with weldable and robust MXene-CNTs hybrid films","authors":"Xueyuan Qiu, Xiao Han, Baorui Dong, Meng Zong, Runtong Zhou, Teng Zhang, Pan Wang, Chang Guo, Hejun Li, Jianhua Hao","doi":"10.1016/j.jmst.2024.08.062","DOIUrl":"https://doi.org/10.1016/j.jmst.2024.08.062","url":null,"abstract":"Stimulus-responsive actuators are novel functional devices capable of sensing external stimuli and exhibiting specific deformation responses. MXene, owing to its unique 2D structure and efficient energy conversion efficiency, has bridged the gap in traditional devices and shown great potential for multiple stimulus-responsive actuators. However, the drawbacks of pure MXene films, including susceptibility to oxidation and vulnerability to shear stress, hinder their applications. Through composite modification and structural design strategies, a three-layer structured MXene-carbon nanotubes hybrid film (tHCM) is fabricated, exhibiting a tensile strength and fracture strain of 153.8 MPa and 4.65%, respectively, representing improvements of 598.4% and 226.8% compared to the initial film. Meanwhile, the film maintains excellent stability demonstrating the enhancing effects of hydrogen bonds and densely packed structure. The hybrid films demonstrate unique and facile welding features due to splicing properties, enabling the formation of complex configurations. In terms of electro-/photo-thermal conversion performance, the hybrid film can reach a reasonably high temperature of 250 ℃ at low voltage (2.5 V) and 110.6 ℃ under 150 mW cm<sup>–2</sup> infrared light. Leveraging the thermal expansion mismatch between tHCM and thermoplastic films, an integrated, flexible, and weldable actuator with unique electro/photo-response is developed, and various biomimetic driving applications, particularly, the light-mediated hierarchical transmission and precise motion along predetermined trajectory are realized. This work not only provides an effective strategy for modifying MXene composite films but also advances the design of novel actuators, offering broad application prospects in fields such as stimulus-responsive actuated robots and cargo transportation.","PeriodicalId":16154,"journal":{"name":"Journal of Materials Science & Technology","volume":"9 1","pages":""},"PeriodicalIF":10.9,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142324894","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 : 2024-09-25DOI: 10.1016/j.jmst.2024.09.012
Chao Ding, Huibin Wu, Dong Liu, Robert O. Ritchie, Na Gong, Kun Li, Lawrence E. Murr, Gang Niu
High-strength steel with excellent ductility is pivotal for the formability and safety of critical structural components. Here, a heterogeneous metastable lamellar steel, composed of alternating lamellar ferrite and austenite aligned with the rolling direction, was developed through an innovative combination of warm rolling and immediate annealing processes. This novel design overcomes the strength-ductility trade-off, achieving high ultimate tensile strength (∼1.2 GPa) and excellent uniform elongation (∼78%), pushing the product of ultimate tensile strength and uniform elongation to an ultra-high level (> 90 GPa %). The high tensile strength is attributed to ultrafine lamellar grains and significant work hardening induced by the hetero-deformation and transformation-induced plasticity (TRIP) effect. The exceptional ductility is a result of the synergy of multiple plasticity mechanisms, including (i) the inherent plastic deformation ability of lamellar microstructure and the hetero-deformation-induced hardening in the early deformation period, (ii) the persistent TRIP effect induced by the lamellar austenite with high mechanical stability and the elimination of strain localization caused by prolonged strain hardening due to the coordinated deformation of lamellar austenite and ferrite in the middle deformation period, and (iii) delamination cracking in the late deformation period. This approach adopted in current work offers a straightforward and economically feasible pathway for fabricating advanced high-strength steel with superior performance.
{"title":"Achieving unexpected strength and ductility synergies in heterogeneous metastable lamellar steels","authors":"Chao Ding, Huibin Wu, Dong Liu, Robert O. Ritchie, Na Gong, Kun Li, Lawrence E. Murr, Gang Niu","doi":"10.1016/j.jmst.2024.09.012","DOIUrl":"https://doi.org/10.1016/j.jmst.2024.09.012","url":null,"abstract":"High-strength steel with excellent ductility is pivotal for the formability and safety of critical structural components. Here, a heterogeneous metastable lamellar steel, composed of alternating lamellar ferrite and austenite aligned with the rolling direction, was developed through an innovative combination of warm rolling and immediate annealing processes. This novel design overcomes the strength-ductility trade-off, achieving high ultimate tensile strength (∼1.2 GPa) and excellent uniform elongation (∼78%), pushing the product of ultimate tensile strength and uniform elongation to an ultra-high level (> 90 GPa %). The high tensile strength is attributed to ultrafine lamellar grains and significant work hardening induced by the hetero-deformation and transformation-induced plasticity (TRIP) effect. The exceptional ductility is a result of the synergy of multiple plasticity mechanisms, including (i) the inherent plastic deformation ability of lamellar microstructure and the hetero-deformation-induced hardening in the early deformation period, (ii) the persistent TRIP effect induced by the lamellar austenite with high mechanical stability and the elimination of strain localization caused by prolonged strain hardening due to the coordinated deformation of lamellar austenite and ferrite in the middle deformation period, and (iii) delamination cracking in the late deformation period. This approach adopted in current work offers a straightforward and economically feasible pathway for fabricating advanced high-strength steel with superior performance.","PeriodicalId":16154,"journal":{"name":"Journal of Materials Science & Technology","volume":"22 1","pages":""},"PeriodicalIF":10.9,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142317244","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}
Since the as-cast microstructure benefits dynamic recrystallization (DRX) nucleation, the present research is focused on the microstructure evolution associated with the dendrites and precipitates during the thermal deformation of an ingot without homogenization treatment aiming at exploring a new efficient strategy of ingot cogging for superalloys. The as-cast samples were deformed at the sub-solvus temperature, and the DRX evolution from dendritic arms (DAs) to inter-dendritic regions (IDRs) was discussed based on the observation of the fishnet-like DRX microstructures and the gradient of DRX grain size at IDRs. The difference in the precipitates at DAs and IDRs played an essential role during the deformation and DRX process, which finally resulted in very different microstructures in the two areas. A selective strain-induced grain boundary bulging (SIGBB) mechanism was found to function well and dominate the DRX nucleation at DAs. The grain boundary was able to migrate and bulge to nucleate on the condition that the boundary was located at DAs and had a great difference in dislocation density between its opposite sides at the same time. As for DRX nucleation at IDRs, the particle-stimulated nucleation (PSN) mechanism played a leading role, and the progressive subgrain rotation (PSR) and geometric DRX were two important supplementary mechanisms. The dislocation accumulation around the coarse precipitates at IDR resulted in progressive orientation rotation, which would generate DRX nuclei once the maximum misorientation there was sufficient to form a high-angle boundary with the matrix. The PSR or geometric DRX functioned at the severely elongated IDRs at the later stage of deformation, depending on the thickness of the elongated IDRs. The uniform microstructure was obtained by the deformation without homogenization and the subsequent annealing treatment. The smaller strain, the lower annealing temperature, and the much shorter soaking time requested in the above process lead to a smaller risk of cracking and a lower consumption of energy during the ingot-cogging process.
{"title":"A novel strategy for ingot cogging without homogenization: Dynamical recrystallization and nucleation mechanisms associated with as-cast dendrites of nickel-based superalloys","authors":"B.C. Xie, Y.W. Luo, Z.T. Wang, Q.Q. Meng, Y.Q. Ning, M.W. Fu","doi":"10.1016/j.jmst.2024.08.061","DOIUrl":"https://doi.org/10.1016/j.jmst.2024.08.061","url":null,"abstract":"Since the as-cast microstructure benefits dynamic recrystallization (DRX) nucleation, the present research is focused on the microstructure evolution associated with the dendrites and precipitates during the thermal deformation of an ingot without homogenization treatment aiming at exploring a new efficient strategy of ingot cogging for superalloys. The as-cast samples were deformed at the sub-solvus temperature, and the DRX evolution from dendritic arms (DAs) to inter-dendritic regions (IDRs) was discussed based on the observation of the fishnet-like DRX microstructures and the gradient of DRX grain size at IDRs. The difference in the precipitates at DAs and IDRs played an essential role during the deformation and DRX process, which finally resulted in very different microstructures in the two areas. A selective strain-induced grain boundary bulging (SIGBB) mechanism was found to function well and dominate the DRX nucleation at DAs. The grain boundary was able to migrate and bulge to nucleate on the condition that the boundary was located at DAs and had a great difference in dislocation density between its opposite sides at the same time. As for DRX nucleation at IDRs, the particle-stimulated nucleation (PSN) mechanism played a leading role, and the progressive subgrain rotation (PSR) and geometric DRX were two important supplementary mechanisms. The dislocation accumulation around the coarse precipitates at IDR resulted in progressive orientation rotation, which would generate DRX nuclei once the maximum misorientation there was sufficient to form a high-angle boundary with the matrix. The PSR or geometric DRX functioned at the severely elongated IDRs at the later stage of deformation, depending on the thickness of the elongated IDRs. The uniform microstructure was obtained by the deformation without homogenization and the subsequent annealing treatment. The smaller strain, the lower annealing temperature, and the much shorter soaking time requested in the above process lead to a smaller risk of cracking and a lower consumption of energy during the ingot-cogging process.","PeriodicalId":16154,"journal":{"name":"Journal of Materials Science & Technology","volume":"65 1","pages":""},"PeriodicalIF":10.9,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142317245","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 : 2024-09-24DOI: 10.1016/j.jmst.2024.08.056
Sivaji Karna, Lang Yuan, Tianyu Zhang, Rimah Al-Aridi, Andrew J. Gross, Daniel Morrall, Timothy Krentz, Dale Hitchcock
AA6061 is a widely used aluminum alloy with significant applications in the aerospace and automotive industries. Despite its popularity, the utilization of additively manufactured AA6061 through the laser powder bed fusion (LPBF) process has been hindered by the pronounced formation of pores and cracks during rapid solidification. This study quantitatively investigated defects, including pores and cracks, and microstructures, including texture, grain size, subgrain structure, and precipitates, of LPBF-manufactured AA6061 across a broad spectrum of laser power and speed combinations. A high relative density of more than 99 % was achieved with a low-power and low-speed condition, specifically 200 W and 100 mm/s, with minimal cracks. Large pores, akin to or exceeding melt pool dimensions, emerged under either low or high energy densities, driven by the lack of fusion and vaporization/denudation mechanisms, respectively. Solidification cracks, confirmed by the fractography, were propagated along grain boundaries and are highly dependent on laser scanning speed. Elevated power and speed exhibited finer grain size with refined subgrain cellular structures and increased precipitates at interdendritic regions. The cooling rate and thermal gradient estimated from thermal analytical solutions explain the microstructures’ characteristics. Nano-sized Si-Fe-Mg enriched precipitates are confirmed in both as-built and heat-treated conditions, whereas T6 heat treatment promotes a uniform distribution with coarsening of those precipitates. The low-power and low-speed conditions demonstrated the highest yield strength, consistent with defect levels. A minimum of 102.3 % increase in yield strength with reduced ductility was observed after heat treatment for all examined conditions. This work sheds light on printing parameters to mitigate the formation of pores and cracks in additively manufactured AA6061, proposing a process window for optimized fabrication and highlighting the potential for enhanced material properties and reduced defects through process control.
{"title":"Microstructural analysis and defect characterization of additively manufactured AA6061 aluminum alloy via laser powder bed fusion","authors":"Sivaji Karna, Lang Yuan, Tianyu Zhang, Rimah Al-Aridi, Andrew J. Gross, Daniel Morrall, Timothy Krentz, Dale Hitchcock","doi":"10.1016/j.jmst.2024.08.056","DOIUrl":"https://doi.org/10.1016/j.jmst.2024.08.056","url":null,"abstract":"AA6061 is a widely used aluminum alloy with significant applications in the aerospace and automotive industries. Despite its popularity, the utilization of additively manufactured AA6061 through the laser powder bed fusion (LPBF) process has been hindered by the pronounced formation of pores and cracks during rapid solidification. This study quantitatively investigated defects, including pores and cracks, and microstructures, including texture, grain size, subgrain structure, and precipitates, of LPBF-manufactured AA6061 across a broad spectrum of laser power and speed combinations. A high relative density of more than 99 % was achieved with a low-power and low-speed condition, specifically 200 W and 100 mm/s, with minimal cracks. Large pores, akin to or exceeding melt pool dimensions, emerged under either low or high energy densities, driven by the lack of fusion and vaporization/denudation mechanisms, respectively. Solidification cracks, confirmed by the fractography, were propagated along grain boundaries and are highly dependent on laser scanning speed. Elevated power and speed exhibited finer grain size with refined subgrain cellular structures and increased precipitates at interdendritic regions. The cooling rate and thermal gradient estimated from thermal analytical solutions explain the microstructures’ characteristics. Nano-sized Si-Fe-Mg enriched precipitates are confirmed in both as-built and heat-treated conditions, whereas T6 heat treatment promotes a uniform distribution with coarsening of those precipitates. The low-power and low-speed conditions demonstrated the highest yield strength, consistent with defect levels. A minimum of 102.3 % increase in yield strength with reduced ductility was observed after heat treatment for all examined conditions. This work sheds light on printing parameters to mitigate the formation of pores and cracks in additively manufactured AA6061, proposing a process window for optimized fabrication and highlighting the potential for enhanced material properties and reduced defects through process control.","PeriodicalId":16154,"journal":{"name":"Journal of Materials Science & Technology","volume":"1 1","pages":""},"PeriodicalIF":10.9,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142313459","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}
L10-FePt nanoparticles (NPs) are urgently anticipated because of their promising applications. However, the preparation of the NPs with both of high ordering degree and super-fine size is still a challenge. Inspired by recent studies on the effect of vacancy defects on structural ordering, we proposed an intentional vacancy defect design strategy for directly synthesizing highly ordered FePt NPs. In the present work, we used the first-principle calculations to investigate the influence of doping typical elements (Cu, Ag, and Pb) on the vacancy formation energy (Evac) of FePt NPs. The vacancy defects were effectively formed by introducing elements of larger atomic radii and higher propensity for segregation into the FePt lattice, facilitating the diffusion of Fe and Pt atoms. The Pb doping showed remarkable efficacy in promoting the ordering transition. Experimentally, wet-chemical synthesis confirmed the success of the proposed strategy in achieving highly ordered L10-FePt NPs with exceptional magnetic properties and super-fine size (ordering degree of 0.896, impressive coercivity of 21.74 kOe, and small particle size of 9.02 nm). Additionally, we have deduced a diffusion model elucidating the formation process of the ordered FePt NPs, focusing on the migration of Pb atoms from the center to the surface of the particles. This migration is demonstrated to generate more vacancies and promote the transition to the ordered L10-FePt phase. The findings of this research offer valuable insights into synthesizing highly ordered and ultrafine L10-type nanomaterials.
{"title":"Vacancy defect strategy for enhancing structural ordering and magnetic performance of L10-FePt nanoparticles","authors":"Dong Zhao, Qunshou Wang, Yanglin Wang, Kunhua Zhang, Ming Wen, Chuangwei Liu, Dake Xu, Jianjun Wang, Qiang Wang, Wenli Pei","doi":"10.1016/j.jmst.2024.08.060","DOIUrl":"https://doi.org/10.1016/j.jmst.2024.08.060","url":null,"abstract":"<em>L</em>1<sub>0</sub>-FePt nanoparticles (NPs) are urgently anticipated because of their promising applications. However, the preparation of the NPs with both of high ordering degree and super-fine size is still a challenge. Inspired by recent studies on the effect of vacancy defects on structural ordering, we proposed an intentional vacancy defect design strategy for directly synthesizing highly ordered FePt NPs. In the present work, we used the first-principle calculations to investigate the influence of doping typical elements (Cu, Ag, and Pb) on the vacancy formation energy (<em>E</em><sub>vac</sub>) of FePt NPs. The vacancy defects were effectively formed by introducing elements of larger atomic radii and higher propensity for segregation into the FePt lattice, facilitating the diffusion of Fe and Pt atoms. The Pb doping showed remarkable efficacy in promoting the ordering transition. Experimentally, wet-chemical synthesis confirmed the success of the proposed strategy in achieving highly ordered <em>L</em>1<sub>0</sub>-FePt NPs with exceptional magnetic properties and super-fine size (ordering degree of 0.896, impressive coercivity of 21.74 kOe, and small particle size of 9.02 nm). Additionally, we have deduced a diffusion model elucidating the formation process of the ordered FePt NPs, focusing on the migration of Pb atoms from the center to the surface of the particles. This migration is demonstrated to generate more vacancies and promote the transition to the ordered <em>L</em>1<sub>0</sub>-FePt phase. The findings of this research offer valuable insights into synthesizing highly ordered and ultrafine <em>L</em>1<sub>0</sub>-type nanomaterials.","PeriodicalId":16154,"journal":{"name":"Journal of Materials Science & Technology","volume":"23 1","pages":""},"PeriodicalIF":10.9,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142313460","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 : 2024-09-24DOI: 10.1016/j.jmst.2024.09.009
Mohsen Tamtaji, William A. Goddard, Ziyang Hu, GuanHua Chen
Single and dual-atom catalysts (SACs and DACs) on single-layer graphene are widely investigated for a wide range of electrochemical reactions. However, the effect of van der Waals interactions on the activity of these catalysts has not been investigated through systematic high throughput screening. Here we introduce the concept of van der Waals interactions through a double-layer DAC structure which has axial d orbital modification towards enhanced CO2 reduction reaction (CO2RR), hydrogen evolution reaction (HER), oxygen reduction reaction (ORR), and oxygen evolution reaction (OER). We applied density functional theory (DFT) to screen 3d, 4d, and 5d transition metals supported by double-layer nitrogen-doped graphene, denoted as M2N8. We sought catalysts with high thermodynamic and electrochemical stabilities along with low overpotentials for CO2RR, ORR, OER, or HER. We find that HER can take place inside the van der Waals gap of V2N8 and Co2N8 leading to overpotentials of 0.10 and 0.16 V. Moreover, ORR and OER can take place on the surface of Fe2N8 and Ir2N8, respectively, leading to overpotentials of 0.39 and 0.37 V. DFT predicts a CO2RR overpotential of 0.85 V towards CO on the surface of Co2N8 along with the HER overpotential of 0.16 V inside the van der Waals gap of Co2N8 towards the production of syngas (CO+H2). This paper provides fundamental insights into the design of advanced multi-layer catalysts by applying the concept of van der Waals interactions for electrochemistry at room temperature.
单层石墨烯上的单原子和双原子催化剂（SACs 和 DACs）已被广泛研究用于多种电化学反应。然而，范德华相互作用对这些催化剂活性的影响尚未通过系统的高通量筛选得到研究。在此，我们通过双层 DAC 结构引入了范德华相互作用的概念，该结构具有轴向 d 轨道修饰，可增强二氧化碳还原反应（CO2RR）、氢进化反应（HER）、氧还原反应（ORR）和氧进化反应（OER）。我们应用密度泛函理论（DFT）筛选了由双层掺氮石墨烯（记为 M2N8）支撑的 3d、4d 和 5d 过渡金属。我们寻找的催化剂具有较高的热力学和电化学稳定性，以及较低的 CO2RR、ORR、OER 或 HER 过电位。我们发现，HER 可在 V2N8 和 Co2N8 的范德华间隙内发生，过电势分别为 0.10 和 0.16 V。此外，ORR 和 OER 可分别在 Fe2N8 和 Ir2N8 表面发生，导致 0.39 V 和 0.37 V 的过电位。根据 DFT 预测，在 Co2N8 表面对 CO 的 CO2RR 过电位为 0.85 V，而在 Co2N8 的范德华间隙内对合成气（CO+H2）的 HER 过电位为 0.16 V。本文通过在室温电化学中应用范德华相互作用的概念，为设计先进的多层催化剂提供了基本见解。
{"title":"High-throughput screening of axially bonded dual atom catalysts for enhanced electrocatalytic reactions: The effect of van der Waals interaction","authors":"Mohsen Tamtaji, William A. Goddard, Ziyang Hu, GuanHua Chen","doi":"10.1016/j.jmst.2024.09.009","DOIUrl":"https://doi.org/10.1016/j.jmst.2024.09.009","url":null,"abstract":"Single and dual-atom catalysts (SACs and DACs) on <em>single-layer</em> graphene are widely investigated for a wide range of electrochemical reactions. However, the effect of van der Waals interactions on the activity of these catalysts has not been investigated through systematic high throughput screening. Here we introduce the concept of van der Waals interactions through a <em>double-layer</em> DAC structure which has axial d orbital modification towards enhanced CO<sub>2</sub> reduction reaction (CO<sub>2</sub>RR), hydrogen evolution reaction (HER), oxygen reduction reaction (ORR), and oxygen evolution reaction (OER). We applied density functional theory (DFT) to screen 3d, 4d, and 5d transition metals supported by <em>double-layer</em> nitrogen-doped graphene, denoted as M2N8. We sought catalysts with high thermodynamic and electrochemical stabilities along with low overpotentials for CO<sub>2</sub>RR, ORR, OER, or HER. We find that HER can take place inside the van der Waals gap of V2N8 and Co2N8 leading to overpotentials of 0.10 and 0.16 V. Moreover, ORR and OER can take place on the surface of Fe2N8 and Ir2N8, respectively, leading to overpotentials of 0.39 and 0.37 V. DFT predicts a CO<sub>2</sub>RR overpotential of 0.85 V towards CO on the surface of Co2N8 along with the HER overpotential of 0.16 V inside the van der Waals gap of Co2N8 towards the production of syngas (CO+H<sub>2</sub>). This paper provides fundamental insights into the design of advanced <em>multi-layer</em> catalysts by applying the concept of van der Waals interactions for electrochemistry at room temperature.","PeriodicalId":16154,"journal":{"name":"Journal of Materials Science & Technology","volume":"190 1","pages":""},"PeriodicalIF":10.9,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142313461","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}
The formation of segregated structure has been demonstrated as an effective strategy for achieving exceptional electromagnetic interference (EMI) shielding performance at low filler loadings. However, the acquisition of polymer particles and the formation of interactions with conductive fillers remain significant challenges for polydimethylsiloxane, which are crucial to the construction of a segregated structure. In this work, MXene sheets were functionalized and assembled onto the surface of polydimethylsiloxane microspheres via hydrophobic interaction. Subsequently, functionalized MXene/polydimethylsiloxane (FMP) composites with a segregated structure were fabricated by filtration and hot-pressing. The FMP composite containing 8.22 wt.% MXene exhibited a high electrical conductivity of 99.4 S·m-1 and a satisfactory EMI shielding effectiveness/thickness (EMI SE/d) of 31.3 dB·mm-1. Furthermore, the FMP composite demonstrated excellent reliability with over 90% retention of EMI shielding effectiveness under harsh environments such as ultra-high/low temperatures and acidic/alkaline solutions. Additionally, the photothermal conversion performance of FMP composites and the capacitive sensing performance of the sensor based on FMP composites indicated their potential for managing body temperature and monitoring human movement. Consequently, FMP composites show great promise in wearable electronics for effective electromagnetic interference shielding, thermal management and capacitive sensing.
{"title":"Flexible multifunctional polydimethylsiloxane composites with segregated structure fabricated by hydrophobic interaction for efficient electromagnetic interference shielding","authors":"Weirui Zhang, Zhongjie He, Jinliang Xie, Fangfang Su, Yangyang Xin, Dongdong Yao, Mingxiang Li, Yudeng Wang, Yaping Zheng","doi":"10.1016/j.jmst.2024.08.059","DOIUrl":"https://doi.org/10.1016/j.jmst.2024.08.059","url":null,"abstract":"The formation of segregated structure has been demonstrated as an effective strategy for achieving exceptional electromagnetic interference (EMI) shielding performance at low filler loadings. However, the acquisition of polymer particles and the formation of interactions with conductive fillers remain significant challenges for polydimethylsiloxane, which are crucial to the construction of a segregated structure. In this work, MXene sheets were functionalized and assembled onto the surface of polydimethylsiloxane microspheres via hydrophobic interaction. Subsequently, functionalized MXene/polydimethylsiloxane (FMP) composites with a segregated structure were fabricated by filtration and hot-pressing. The FMP composite containing 8.22 wt.% MXene exhibited a high electrical conductivity of 99.4 S·m<sup>-1</sup> and a satisfactory EMI shielding effectiveness/thickness (EMI SE/d) of 31.3 dB·mm<sup>-1</sup>. Furthermore, the FMP composite demonstrated excellent reliability with over 90% retention of EMI shielding effectiveness under harsh environments such as ultra-high/low temperatures and acidic/alkaline solutions. Additionally, the photothermal conversion performance of FMP composites and the capacitive sensing performance of the sensor based on FMP composites indicated their potential for managing body temperature and monitoring human movement. Consequently, FMP composites show great promise in wearable electronics for effective electromagnetic interference shielding, thermal management and capacitive sensing.","PeriodicalId":16154,"journal":{"name":"Journal of Materials Science & Technology","volume":"30 1","pages":""},"PeriodicalIF":10.9,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142313458","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 : 2024-09-24DOI: 10.1016/j.jmst.2024.09.011
Zhiyuan Zhang, Zhiming Zhang, Jianqiu Wang, Hongliang Ming, Haipeng Zhu, Tichun Dan, Ruoyu Wang, Beibei Gao, En-Hou Han
The effect of polyacrylic acid (PAA) on the corrosion behavior of Alloy 690 in simulated pressurized water reactor secondary water was investigated. The duplex oxide film structure, consisting of a Ni-rich outer layer and a Cr-rich inner layer, was maintained regardless of PAA presence. PAA inhibited the growth of outer Ni-rich particles while promoting Cr enrichment in the inner layer and inducing its amorphization, both enhancing oxidation resistance. However, excess PAA (≥ 500 ppb) suppressed protective oxide formation during initial oxidation, leading to oxygen penetration into the matrix. A PAA concentration of around 250 ppb is considered optimal for steam generators, as it provides the benefits of PAA without adverse effects on the alloy.
{"title":"Effect of polyacrylic acid on the corrosion behavior of Alloy 690 in pressurized water reactor secondary water","authors":"Zhiyuan Zhang, Zhiming Zhang, Jianqiu Wang, Hongliang Ming, Haipeng Zhu, Tichun Dan, Ruoyu Wang, Beibei Gao, En-Hou Han","doi":"10.1016/j.jmst.2024.09.011","DOIUrl":"https://doi.org/10.1016/j.jmst.2024.09.011","url":null,"abstract":"The effect of polyacrylic acid (PAA) on the corrosion behavior of Alloy 690 in simulated pressurized water reactor secondary water was investigated. The duplex oxide film structure, consisting of a Ni-rich outer layer and a Cr-rich inner layer, was maintained regardless of PAA presence. PAA inhibited the growth of outer Ni-rich particles while promoting Cr enrichment in the inner layer and inducing its amorphization, both enhancing oxidation resistance. However, excess PAA (≥ 500 ppb) suppressed protective oxide formation during initial oxidation, leading to oxygen penetration into the matrix. A PAA concentration of around 250 ppb is considered optimal for steam generators, as it provides the benefits of PAA without adverse effects on the alloy.","PeriodicalId":16154,"journal":{"name":"Journal of Materials Science & Technology","volume":"11 1","pages":""},"PeriodicalIF":10.9,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142313456","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 : 2024-09-24DOI: 10.1016/j.jmst.2024.08.058
Yu Tian, Fei Chen
Pronounced compositional fluctuations in CrMnFeCoNi high-entropy alloys (HEAs) lead to variations of the stacking-fault energy (SFE), which dominates the dislocation behavior and mechanical properties. However, studies on the underlying dislocation behaviors and deformation mechanisms as a function of composition (Cr/Ni ratio) within CrMnFeCoNi HEAs are largely lacking, which hinders further understanding of the composition-structure-property relationships for the rational design of HEAs. Atomistic simulations were employed in this study to investigate the core structures and dynamic behaviors of a/2<110> edge dislocations in non-equiatomic CrMnFeCoNi HEA, as well as its plasticity mechanisms. The results show that the core structure of a/2<110> edge dislocations is planar after energy minimization, but with significant variations in the separation distance between two partial dislocations along the dislocation line owing to the complex local composition. The effects of the Cr/Ni ratio on the dislocation-solute interactions during dislocation gliding were calculated and discussed. Additionally, snapshots of dislocation motion under shear stress were analyzed. The observations indicate that the strengthening of the non-equiatomic CrMnFeCoNi HEA with increasing Cr concentration is not contributed by the expected solute/dislocation interactions, but the observed events of edge extended dislocation climbing through jog nucleation. The unusual but reasonable dislocation climbing phenomenon and the resultant strengthening observed in this study open extraordinary opportunities for obtaining outstanding mechanical properties in non-equiatomic CrMnFeCoNi HEAs by tailoring the compositional variations.
铬锰铁钴镍（CrMnFeCoNi）高熵合金（HEAs）中明显的成分波动会导致堆错能（SFE）的变化，而堆错能主导着位错行为和机械性能。然而，关于铬锰铁钴镍高熵合金中的基本位错行为和变形机制与成分（铬/镍比）的函数关系的研究还很缺乏，这阻碍了对成分-结构-性能关系的进一步了解，从而无法合理设计高熵合金。本研究采用原子模拟研究了非等原子铬锰铁钴镍 HEA 中 a/2<110> 边缘位错的核心结构和动态行为及其塑性机制。结果表明，能量最小化后，a/2<110>边缘位错的核心结构是平面的，但由于局部成分复杂，沿位错线两个部分位错之间的分离距离变化很大。计算并讨论了在差排滑行过程中，铬/镍比对差排-固溶体相互作用的影响。此外，还分析了剪切应力下差排运动的快照。观察结果表明，随着铬浓度的增加，非等原子铬锰铁钴镍 HEA 的强化不是由预期的溶质/差排相互作用造成的，而是通过点动成核观察到的边缘扩展差排爬行事件。本研究中观察到的不寻常但合理的位错攀升现象和由此产生的强化，为通过调整成分变化在非等原子铬锰铁钴尼 HEA 中获得出色的机械性能提供了难得的机会。
{"title":"Atomistic simulations of dislocation behaviors in Cr-Mn-Fe-Co-Ni high-entropy alloys with different Cr/Ni ratio","authors":"Yu Tian, Fei Chen","doi":"10.1016/j.jmst.2024.08.058","DOIUrl":"https://doi.org/10.1016/j.jmst.2024.08.058","url":null,"abstract":"Pronounced compositional fluctuations in CrMnFeCoNi high-entropy alloys (HEAs) lead to variations of the stacking-fault energy (SFE), which dominates the dislocation behavior and mechanical properties. However, studies on the underlying dislocation behaviors and deformation mechanisms as a function of composition (Cr/Ni ratio) within CrMnFeCoNi HEAs are largely lacking, which hinders further understanding of the composition-structure-property relationships for the rational design of HEAs. Atomistic simulations were employed in this study to investigate the core structures and dynamic behaviors of a/2<110> edge dislocations in non-equiatomic CrMnFeCoNi HEA, as well as its plasticity mechanisms. The results show that the core structure of a/2<110> edge dislocations is planar after energy minimization, but with significant variations in the separation distance between two partial dislocations along the dislocation line owing to the complex local composition. The effects of the Cr/Ni ratio on the dislocation-solute interactions during dislocation gliding were calculated and discussed. Additionally, snapshots of dislocation motion under shear stress were analyzed. The observations indicate that the strengthening of the non-equiatomic CrMnFeCoNi HEA with increasing Cr concentration is not contributed by the expected solute/dislocation interactions, but the observed events of edge extended dislocation climbing through jog nucleation. The unusual but reasonable dislocation climbing phenomenon and the resultant strengthening observed in this study open extraordinary opportunities for obtaining outstanding mechanical properties in non-equiatomic CrMnFeCoNi HEAs by tailoring the compositional variations.","PeriodicalId":16154,"journal":{"name":"Journal of Materials Science & Technology","volume":"24 1","pages":""},"PeriodicalIF":10.9,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142313526","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 : 2024-09-24DOI: 10.1016/j.jmst.2024.09.010
Yan Zou, Lingfei Cao, Xiaodong Wu, Chenglin Mou, Songbai Tang
High-strength Al-Zn-Mg-Cu alloys are widely utilized, but their strength deteriorates as strengthening precipitates coarsen rapidly at elevated temperatures, limiting their applications above 150°C. This study systematically investigates the microstructure evolution and its impact on the properties of peak-aged Al-Zn-Mg-Cu alloys with varying Zn/Mg ratios during thermal exposure at a series of temperatures from 150 to 300°C for 500 h. The results reveal that alloys A1 and A2 with an optimal Zn/Mg ratio (1.50−2.14) and relatively lower (Zn + Mg) content (7.0−8.8 wt.%), exhibit superior heat resistance properties compared to the other three alloys. Despite having lower strength relative to alloys with higher solute content, peak-aged alloys A1 and A2 retain the highest strength after thermal exposure. This performance is attributed to the high proportion (over 80%) of T′/T phases in the precipitates for alloys A1 and A2, which demonstrate better thermal stability in comparison to η′/η phases. Additionally, the lower solute content reduces the driving force for diffusion of Zn and Mg atoms, thus inhibiting the coarsening of precipitates. Moreover, the study elucidates that the coarsening mechanism of precipitates transitions from interfacial diffusion control at 150°C to matrix diffusion control at 200−300°C. These insights into the composition-dependent coarsening behavior of precipitates in dual-phase strengthened Al-Zn-Mg-Cu alloys offer valuable guidance for designing heat-resistant aluminum alloys with enhanced performance at elevated temperatures.
{"title":"Revealing the coarsening behavior of precipitates and its effect on the thermal stability in Tʹ and ηʹ dual-phase strengthened Al-Zn-Mg-Cu alloys","authors":"Yan Zou, Lingfei Cao, Xiaodong Wu, Chenglin Mou, Songbai Tang","doi":"10.1016/j.jmst.2024.09.010","DOIUrl":"https://doi.org/10.1016/j.jmst.2024.09.010","url":null,"abstract":"High-strength Al-Zn-Mg-Cu alloys are widely utilized, but their strength deteriorates as strengthening precipitates coarsen rapidly at elevated temperatures, limiting their applications above 150°C. This study systematically investigates the microstructure evolution and its impact on the properties of peak-aged Al-Zn-Mg-Cu alloys with varying Zn/Mg ratios during thermal exposure at a series of temperatures from 150 to 300°C for 500 h. The results reveal that alloys A1 and A2 with an optimal Zn/Mg ratio (1.50−2.14) and relatively lower (Zn + Mg) content (7.0−8.8 wt.%), exhibit superior heat resistance properties compared to the other three alloys. Despite having lower strength relative to alloys with higher solute content, peak-aged alloys A1 and A2 retain the highest strength after thermal exposure. This performance is attributed to the high proportion (over 80%) of T′/T phases in the precipitates for alloys A1 and A2, which demonstrate better thermal stability in comparison to η′/η phases. Additionally, the lower solute content reduces the driving force for diffusion of Zn and Mg atoms, thus inhibiting the coarsening of precipitates. Moreover, the study elucidates that the coarsening mechanism of precipitates transitions from interfacial diffusion control at 150°C to matrix diffusion control at 200−300°C. These insights into the composition-dependent coarsening behavior of precipitates in dual-phase strengthened Al-Zn-Mg-Cu alloys offer valuable guidance for designing heat-resistant aluminum alloys with enhanced performance at elevated temperatures.","PeriodicalId":16154,"journal":{"name":"Journal of Materials Science & Technology","volume":"46 1","pages":""},"PeriodicalIF":10.9,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142313457","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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