Pub Date : 2024-09-19DOI: 10.1016/j.vacuum.2024.113666
The traditional wisdom seems to suggest that yttrium can be added with oxygen to form inert oxides to prevent oxygen contamination during the MGs fabricated process. Here, the effects of yttrium-doped on the microstructure evolution of the Zr-based MG composite coatings were systematically investigated by laser melting deposition technology. We firstly reported that the yttrium oxides were not completely in an inert state, but as the heterogeneous nucleation core with epitaxial growth of the CuZr intermetallic compound with simple cubic structure, under the influence of sufficient heat input and a low cooling rates, while would be inhibited with insufficient thermal input and high cooling rates.
{"title":"Effect of yttrium and oxygen combination on the microstructure of Zr-Cu-Ni-Al metallic glass","authors":"","doi":"10.1016/j.vacuum.2024.113666","DOIUrl":"10.1016/j.vacuum.2024.113666","url":null,"abstract":"<div><div>The traditional wisdom seems to suggest that yttrium can be added with oxygen to form inert oxides to prevent oxygen contamination during the MGs fabricated process. Here, the effects of yttrium-doped on the microstructure evolution of the Zr-based MG composite coatings were systematically investigated by laser melting deposition technology. We firstly reported that the yttrium oxides were not completely in an inert state, but as the heterogeneous nucleation core with epitaxial growth of the CuZr intermetallic compound with simple cubic structure, under the influence of sufficient heat input and a low cooling rates, while would be inhibited with insufficient thermal input and high cooling rates.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":null,"pages":null},"PeriodicalIF":3.8,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142315328","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-09-19DOI: 10.1016/j.vacuum.2024.113670
The service conditions of high-entropy alloys (HEAs) joints brazed with conventional filler metals (FMs) can be confined because few HEAs phases generate in the braze zone. In this study, a multicomponent CoCrFeNiNb0.5 eutectic HEAs (EHEAs) FM was developed to braze Al0.3CoCrFeNi HEAs in vacuum, the braze zone mainly consisted of face-centered cubic (FCC) and Laves lamellar structure, exhibiting a superior metallurgical compatibility with the Al0.3CoCrFeNi base metals (BMs). The shear strength and shear displacement of brazed joints reached 461 MPa/1.35 mm at room temperature (RT), 741 MPa/1.42 mm at −196 °C and 380 MPa/1.62 mm at 700 °C, respectively. This strategy can stimulate the fabrication and wide-temperature range applications of HEAs brazed components by exploiting the structural and performance merits of EHEAs FMs.
{"title":"Vacuum brazing of Al0.3CoCrFeNi high-entropy alloys with CoCrFeNiNb0.5 eutectic filler metal for wide-temperature range application","authors":"","doi":"10.1016/j.vacuum.2024.113670","DOIUrl":"10.1016/j.vacuum.2024.113670","url":null,"abstract":"<div><div>The service conditions of high-entropy alloys (HEAs) joints brazed with conventional filler metals (FMs) can be confined because few HEAs phases generate in the braze zone. In this study, a multicomponent CoCrFeNiNb<sub>0.5</sub> eutectic HEAs (EHEAs) FM was developed to braze Al<sub>0.3</sub>CoCrFeNi HEAs in vacuum, the braze zone mainly consisted of face-centered cubic (FCC) and Laves lamellar structure, exhibiting a superior metallurgical compatibility with the Al<sub>0.3</sub>CoCrFeNi base metals (BMs). The shear strength and shear displacement of brazed joints reached 461 MPa/1.35 mm at room temperature (RT), 741 MPa/1.42 mm at −196 °C and 380 MPa/1.62 mm at 700 °C, respectively. This strategy can stimulate the fabrication and wide-temperature range applications of HEAs brazed components by exploiting the structural and performance merits of EHEAs FMs.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":null,"pages":null},"PeriodicalIF":3.8,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142357722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-09-18DOI: 10.1016/j.vacuum.2024.113637
The novel process known as ultrasonic-assisted laser shock peening (ULSP) is conducted on hot rolled Ti6Al4V titanium alloy with polished surface to improve its cavitation erosion (CE) resistance. The microstructure and phase structure were investigated by transmission electron microscope and X-Ray diffractometer. The microhardness and residual stress were measured by microhardness tester and X-Ray residual stress analyzer. After that, the CE mass loss and morphology were analyzed through high-precision analytical balance and scanning electron microscope to reveal the CE resistance mechanism of ULSP. The results show that ULSP treatment causes plastic deformation at the surface layer, resulting in refined grains and complex dislocation structures. The aforementioned process produces a hardened layer and compressive residual stress (CRS) layer with notable amplitude and deep influence. The surface microhardness of the ULSP-9J specimen is 410 ± 4 HV, which is a 14.8 % increase compared to the LSP-9J specimen. The CRS of the ULSP-9J specimen is −329 ± 6 MPa. As a result, it is vital in preventing the formation and propagation of CE cracks, strengthening the material's resistance to CE damage, reducing mass loss, and enhancing the overall morphology of CE.
对表面抛光的热轧 Ti6Al4V 钛合金进行了称为超声波辅助激光冲击强化（ULSP）的新工艺，以提高其抗气蚀（CE）性能。透射电子显微镜和 X 射线衍射仪对微观结构和相结构进行了研究。用显微硬度计和 X 射线残余应力分析仪测量了显微硬度和残余应力。随后，通过高精度分析天平和扫描电子显微镜分析了 CE 质量损失和形貌，揭示了 ULSP 的抗 CE 机理。结果表明，ULSP 处理会导致表层发生塑性变形，从而产生细化晶粒和复杂的位错结构。上述处理过程产生了硬化层和压缩残余应力（CRS）层，其影响幅度大，影响程度深。ULSP-9J 试样的表面显微硬度为 410 ± 4 HV，比 LSP-9J 试样提高了 14.8%。ULSP-9J 试样的 CRS 为 -329 ± 6 MPa。因此，ULSP-9J 对防止 CE 裂纹的形成和扩展、增强材料对 CE 损伤的抵抗力、减少质量损失以及改善 CE 的整体形态至关重要。
{"title":"Investigation into the cavitation erosion of rolled Ti6Al4V titanium alloy strengthened by the ultrasonic-assisted laser shock peening process","authors":"","doi":"10.1016/j.vacuum.2024.113637","DOIUrl":"10.1016/j.vacuum.2024.113637","url":null,"abstract":"<div><div>The novel process known as ultrasonic-assisted laser shock peening (ULSP) is conducted on hot rolled Ti6Al4V titanium alloy with polished surface to improve its cavitation erosion (CE) resistance. The microstructure and phase structure were investigated by transmission electron microscope and X-Ray diffractometer. The microhardness and residual stress were measured by microhardness tester and X-Ray residual stress analyzer. After that, the CE mass loss and morphology were analyzed through high-precision analytical balance and scanning electron microscope to reveal the CE resistance mechanism of ULSP. The results show that ULSP treatment causes plastic deformation at the surface layer, resulting in refined grains and complex dislocation structures. The aforementioned process produces a hardened layer and compressive residual stress (CRS) layer with notable amplitude and deep influence. The surface microhardness of the ULSP-9J specimen is 410 ± 4 HV, which is a 14.8 % increase compared to the LSP-9J specimen. The CRS of the ULSP-9J specimen is −329 ± 6 MPa. As a result, it is vital in preventing the formation and propagation of CE cracks, strengthening the material's resistance to CE damage, reducing mass loss, and enhancing the overall morphology of CE.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":null,"pages":null},"PeriodicalIF":3.8,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142323236","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-09-18DOI: 10.1016/j.vacuum.2024.113662
The β/βo phase in β-solidified TiAl alloys plays a contradictory role in improving processability at high temperatures but deteriorating performance at service temperature due to its ordering transformation. After exerting its positive role during thermomechanical processing, it must be eliminated or reduced to a minimum through post-heat treatment. In this study, the microstructural evolution of the pre-strained Ti-43.24Al-8.42Nb-0.20W-0.21B-0.24Y alloy on post-heat treatment is investigated, and a quantitative relationship between βo phase content and the pre-strain is established. Due to the difference in driving force of phase transformation, with decreasing pre-strain the microstructure displays varied characteristics from a mixed structure comprising (α2+γ) lamellar colonies, γ blocks, and βo phase, to a nearly-lamellar structure after post-heat treatment at 1270 °C/4h/FC. Only if the pre-strain is less than 0.78, a refined nearly-lamellar structure can be achieved. This work provides important theoretical guidance for practical forging processing of β-solidified TiAl alloys.
{"title":"Quantitative analysis on microstructure characteristic of pre-strained β-solidified TiAl alloy during post-heat treatment","authors":"","doi":"10.1016/j.vacuum.2024.113662","DOIUrl":"10.1016/j.vacuum.2024.113662","url":null,"abstract":"<div><div>The β/βo phase in β-solidified TiAl alloys plays a contradictory role in improving processability at high temperatures but deteriorating performance at service temperature due to its ordering transformation. After exerting its positive role during thermomechanical processing, it must be eliminated or reduced to a minimum through post-heat treatment. In this study, the microstructural evolution of the pre-strained Ti-43.24Al-8.42Nb-0.20W-0.21B-0.24Y alloy on post-heat treatment is investigated, and a quantitative relationship between β<sub>o</sub> phase content and the pre-strain is established. Due to the difference in driving force of phase transformation, with decreasing pre-strain the microstructure displays varied characteristics from a mixed structure comprising (α<sub>2</sub>+γ) lamellar colonies, γ blocks, and βo phase, to a nearly-lamellar structure after post-heat treatment at 1270 °C/4h/FC. Only if the pre-strain is less than 0.78, a refined nearly-lamellar structure can be achieved. This work provides important theoretical guidance for practical forging processing of β-solidified TiAl alloys.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":null,"pages":null},"PeriodicalIF":3.8,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142310775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-09-18DOI: 10.1016/j.vacuum.2024.113643
304 stainless-steel has excellent mechanical properties and is commonly used in ultra-precision instrumentation. Nevertheless, the research on the intricate nano tribological behavior of 304 stainless-steel during ultra-precision machining remains limited. In this work, the tribological behavior of 304 stainless-steel is investigated at different indentation depths and scratching velocities by molecular dynamics (MD) simulations and nano-scratch tests. The results show that higher indentation depths lead to more serious damage on the surface and subsurface of 304 stainless-steel. The friction force and friction coefficient also increase significantly with higher indentation depths. It is worth noting that the dislocation density is much smaller at the low-indentation depth, which is due to the large-scale dislocation annihilation at this depth. As the scratch velocity increases, the subsurface shear stress decreases, the dislocation length rises, and it is accompanied by the generation of V-shaped dislocations, which are caused by dislocation entanglement within the substrate. In addition, nano-scratch tests were performed and similar trends were obtained by comparing the results with simulations. This work provides theoretical guidance for a deeper understanding of the deformation behavior of 304 stainless-steel during nano-scratching and its engineering applications at the micron and nano-meter scales.
{"title":"Nano-tribological behavior and structural evolution of 304 stainless-steel by molecular dynamics simulation and experiment","authors":"","doi":"10.1016/j.vacuum.2024.113643","DOIUrl":"10.1016/j.vacuum.2024.113643","url":null,"abstract":"<div><div>304 stainless-steel has excellent mechanical properties and is commonly used in ultra-precision instrumentation. Nevertheless, the research on the intricate nano tribological behavior of 304 stainless-steel during ultra-precision machining remains limited. In this work, the tribological behavior of 304 stainless-steel is investigated at different indentation depths and scratching velocities by molecular dynamics (MD) simulations and nano-scratch tests. The results show that higher indentation depths lead to more serious damage on the surface and subsurface of 304 stainless-steel. The friction force and friction coefficient also increase significantly with higher indentation depths. It is worth noting that the dislocation density is much smaller at the low-indentation depth, which is due to the large-scale dislocation annihilation at this depth. As the scratch velocity increases, the subsurface shear stress decreases, the dislocation length rises, and it is accompanied by the generation of V-shaped dislocations, which are caused by dislocation entanglement within the substrate. In addition, nano-scratch tests were performed and similar trends were obtained by comparing the results with simulations. This work provides theoretical guidance for a deeper understanding of the deformation behavior of 304 stainless-steel during nano-scratching and its engineering applications at the micron and nano-meter scales.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":null,"pages":null},"PeriodicalIF":3.8,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142310779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-09-18DOI: 10.1016/j.vacuum.2024.113664
Vanadium dioxide (VO2) can spontaneously regulate solar heat according to the ambient temperature, and has great application potential as a candidate for smart glass. However, its Tc, ΔTc and ΔH cannot be coordinated at the same time, and commercial use is greatly hindered. W-doped VO2 powders were prepared by the hydrothermal method under an argon atmosphere. Nanoflowers, nanorods, and other morphologies of W-doped VO2 were characterized. The test results showed that W doping could reduce the Tc of VO2 to 33.5 °C, ΔTc < 10 °C, and with high ΔH (ΔH ≈ 36.98 J/g). The phase transition behavior and morphology change mechanism of W-doped VO2 were investigated. The transformation of B and M phases was controlled by changing the annealing temperature, and W-VO2(M) powders with good phase transition properties were finally produced to meet the requirements of the practical application of smart glass materials.
二氧化钒（VO2）可根据环境温度自发调节太阳热量，作为智能玻璃的候选材料具有巨大的应用潜力。然而，二氧化钒的Tc、ΔTc和ΔH不能同时协调，商业应用受到很大阻碍。我们在氩气环境下采用水热法制备了掺 W 的 VO2 粉末。对掺杂 W 的 VO2 的纳米花、纳米棒和其他形态进行了表征。测试结果表明，掺杂 W 能使 VO2 的 Tc 降低到 33.5 °C，ΔTc < 10 °C，并具有较高的ΔH（ΔH ≈ 36.98 J/g）。研究了掺 W VO2 的相变行为和形态变化机理。通过改变退火温度控制了B相和M相的转变，最终制备出具有良好相变特性的W-VO2（M）粉末，满足了智能玻璃材料的实际应用要求。
{"title":"Study of B/M phase transition and phase transition properties of annealing-tuned high phase transition latent heat of W-VO2 nanorods","authors":"","doi":"10.1016/j.vacuum.2024.113664","DOIUrl":"10.1016/j.vacuum.2024.113664","url":null,"abstract":"<div><div>Vanadium dioxide (VO<sub>2</sub>) can spontaneously regulate solar heat according to the ambient temperature, and has great application potential as a candidate for smart glass. However, its <em>T</em><sub><em>c</em></sub>, <em>ΔT</em><sub><em>c</em></sub> and <em>ΔH</em> cannot be coordinated at the same time, and commercial use is greatly hindered. W-doped VO<sub>2</sub> powders were prepared by the hydrothermal method under an argon atmosphere. Nanoflowers, nanorods, and other morphologies of W-doped VO<sub>2</sub> were characterized. The test results showed that W doping could reduce the <em>T</em><sub><em>c</em></sub> of VO<sub>2</sub> to 33.5 °C, <em>ΔT</em><sub><em>c</em></sub> < 10 °C, and with high <em>ΔH</em> (<em>ΔH</em> ≈ 36.98 J/g). The phase transition behavior and morphology change mechanism of W-doped VO<sub>2</sub> were investigated. The transformation of B and M phases was controlled by changing the annealing temperature, and W-VO<sub>2</sub>(M) powders with good phase transition properties were finally produced to meet the requirements of the practical application of smart glass materials.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":null,"pages":null},"PeriodicalIF":3.8,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142310651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-09-17DOI: 10.1016/j.vacuum.2024.113661
This research has successfully performed a new environmentally friendly, safe, and harmless method for fabricating Bi2Ce2O7 nanoparticles (NPs) using Elaeis guineensis Jacq. leaf extracts. Based on the FT-IR measurement, the absorption peak at 635 cm−1 indicates the Bi-O-Ce stretching vibration. The crystalline structure analysis showed that the monoclinic phase of Bi2Ce2O7 NPs was proven by X-ray diffraction characterization. UV–Vis DRS results show that Bi2Ce2O7 NPs have a narrow bandgap of 2.48 eV, indicating their potential for visible light photocatalytic applications. The shape of Bi2Ce2O7 NPs was spherical in agglomeration with an average size of about 30.15 nm. Bi2Ce2O7 NPs exhibited exceptional photocatalytic activity for the degradation of methylene blue (MB) and malachite green (MG) dyes under visible light irradiation. Degradation rates of 99.7 % and 95.8 % for MB and MG, respectively, were achieved within 90 min. This study highlights the potential of utilizing plant-based extracts to produce efficient and environmentally friendly photocatalytic materials.
{"title":"Bi2Ce2O7 nanoparticles synthesized using Elaeis guineensis Jacq. Leaf extracts and its potential for photocatalytic application","authors":"","doi":"10.1016/j.vacuum.2024.113661","DOIUrl":"10.1016/j.vacuum.2024.113661","url":null,"abstract":"<div><div>This research has successfully performed a new environmentally friendly, safe, and harmless method for fabricating Bi<sub>2</sub>Ce<sub>2</sub>O<sub>7</sub> nanoparticles (NPs) using <em>Elaeis guineensis Jacq.</em> leaf extracts. Based on the FT-IR measurement, the absorption peak at 635 cm<sup>−1</sup> indicates the Bi-O-Ce stretching vibration. The crystalline structure analysis showed that the monoclinic phase of Bi<sub>2</sub>Ce<sub>2</sub>O<sub>7</sub> NPs was proven by X-ray diffraction characterization. UV–Vis DRS results show that Bi<sub>2</sub>Ce<sub>2</sub>O<sub>7</sub> NPs have a narrow bandgap of 2.48 eV, indicating their potential for visible light photocatalytic applications. The shape of Bi<sub>2</sub>Ce<sub>2</sub>O<sub>7</sub> NPs was spherical in agglomeration with an average size of about 30.15 nm. Bi<sub>2</sub>Ce<sub>2</sub>O<sub>7</sub> NPs exhibited exceptional photocatalytic activity for the degradation of methylene blue (MB) and malachite green (MG) dyes under visible light irradiation. Degradation rates of 99.7 % and 95.8 % for MB and MG, respectively, were achieved within 90 min. This study highlights the potential of utilizing plant-based extracts to produce efficient and environmentally friendly photocatalytic materials.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":null,"pages":null},"PeriodicalIF":3.8,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142315272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-09-17DOI: 10.1016/j.vacuum.2024.113656
In this paper, a combined transport-defect evolution multiscale model describing the generation and the evolution of microstructure damage in silicon carbide (SiC) induced by focused helium ion beams is developed. In the proposed model, the transport of helium ions and displaced atoms in the SiC substrate and the generation of point defects are described by the Boltzmann transport equations, while the subsequent defect evolution is characterized by a set of rate equations with the contributions of the modeling of the bubble coalescence as well as the substrate swelling. The validity and superiority of the transport equations are verified by comparing the simulation results with the data from experimental measurements and available simulation methods. The subsurface amorphous profile, onsurface swelling profile, and the spatial and size distribution of helium bubbles in a SiC substrate irradiated by focused helium ion beams are simulated using the proposed multiscale model. The damage morphology simulated by the proposed model is in good agreement with the transmission electron microscopy images at different beam energies and doses. This work provides an effective tool for full-stage modeling of complex evolutionary mechanisms of microstructure damage induced by precise and high-throughput helium irradiation.
{"title":"A combined transport-defect evolution model of microstructure damage in silicon carbide induced by precise irradiation of focused helium ion beams","authors":"","doi":"10.1016/j.vacuum.2024.113656","DOIUrl":"10.1016/j.vacuum.2024.113656","url":null,"abstract":"<div><div>In this paper, a combined transport-defect evolution multiscale model describing the generation and the evolution of microstructure damage in silicon carbide (SiC) induced by focused helium ion beams is developed. In the proposed model, the transport of helium ions and displaced atoms in the SiC substrate and the generation of point defects are described by the Boltzmann transport equations, while the subsequent defect evolution is characterized by a set of rate equations with the contributions of the modeling of the bubble coalescence as well as the substrate swelling. The validity and superiority of the transport equations are verified by comparing the simulation results with the data from experimental measurements and available simulation methods. The subsurface amorphous profile, onsurface swelling profile, and the spatial and size distribution of helium bubbles in a SiC substrate irradiated by focused helium ion beams are simulated using the proposed multiscale model. The damage morphology simulated by the proposed model is in good agreement with the transmission electron microscopy images at different beam energies and doses. This work provides an effective tool for full-stage modeling of complex evolutionary mechanisms of microstructure damage induced by precise and high-throughput helium irradiation.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":null,"pages":null},"PeriodicalIF":3.8,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142310777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-09-16DOI: 10.1016/j.vacuum.2024.113658
The carbide/matrix interface in superalloys is susceptible to cracking under mechanical stress, yet the failure mechanisms require further investigation. The cohesive strength and stability of 32 interface models, including HfC(001)/Ni(001), HfC(011)/Ni(001), HfC(111)/Ni(001), HfC(001)/Ni3Al(011), and HfC(111)/Ni3Al(111) within the DZ125 superalloys, were investigated using first-principles calculations and experimental methods. The results indicate that the majority of interfaces demonstrate negative adhesion work (Wad), indicating instability. However, Bridge4 model in HfC(001)/Ni3Al(011) show higher Wad and lower interface energy, suggesting improved stability. The interfacial cohesion is attributable to strong Ni-C covalent bonds. But interfacial fracture toughness results reveal that the majority of models are more susceptible to fracture at the interface. Fracture morphology analysis from tensile tests at room temperature and endurance tests at 760 °C/725 MPa confirms that cracks primarily initiate at the carbide/matrix interface. This study suggests that introducing Ta atoms could improve interface strength, as Ta-rich carbides reduce interfacial energy while increasing elastic energy, resulting in the formation of skeletal structures. The relationship between Hf-rich and Ta-rich carbides and their respective morphology was investigated. The findings provide insights into the failure mechanisms of carbide/matrix interface and offer theoretical guidance for enhancing interface strength in superalloy applications.
超合金中的碳化物/基体界面在机械应力作用下容易开裂，但其失效机理还需要进一步研究。利用第一原理计算和实验方法研究了 DZ125 超合金中 32 个界面模型的内聚强度和稳定性，包括 HfC(001)/Ni(001)、HfC(011)/Ni(001)、HfC(111)/Ni(001)、HfC(001)/Ni3Al(011)和 HfC(111)/Ni3Al(111)。结果表明，大多数界面都显示出负附着功（Wad），表明存在不稳定性。然而，HfC(001)/Ni3Al(011) 中的 Bridge4 模型显示出更高的 Wad 值和更低的界面能，表明稳定性有所提高。界面内聚力可归因于强大的 Ni-C 共价键。但界面断裂韧性结果显示，大多数模型在界面处更容易断裂。室温拉伸试验和 760 °C/725 MPa 耐久性试验的断裂形态分析表明，裂纹主要在碳化物/基体界面处产生。这项研究表明，引入 Ta 原子可提高界面强度，因为富含 Ta 的碳化物可降低界面能，同时提高弹性能，从而形成骨架结构。研究还探讨了富 Hf 和富 Ta 碳化物与各自形态之间的关系。研究结果深入揭示了碳化物/基体界面的失效机制，并为增强超级合金应用中的界面强度提供了理论指导。
{"title":"Atomic-scale bonding strength and failure mechanisms of HfC/Ni/Ni3Al interfaces on low-index crystal planes: A combined HRTEM and first-principles study","authors":"","doi":"10.1016/j.vacuum.2024.113658","DOIUrl":"10.1016/j.vacuum.2024.113658","url":null,"abstract":"<div><div>The carbide/matrix interface in superalloys is susceptible to cracking under mechanical stress, yet the failure mechanisms require further investigation. The cohesive strength and stability of 32 interface models, including HfC(001)/Ni(001), HfC(011)/Ni(001), HfC(111)/Ni(001), HfC(001)/Ni<sub>3</sub>Al(011), and HfC(111)/Ni<sub>3</sub>Al(111) within the DZ125 superalloys, were investigated using first-principles calculations and experimental methods. The results indicate that the majority of interfaces demonstrate negative adhesion work (W<sub>ad</sub>), indicating instability. However, Bridge4 model in HfC(001)/Ni<sub>3</sub>Al(011) show higher W<sub>ad</sub> and lower interface energy, suggesting improved stability. The interfacial cohesion is attributable to strong Ni-C covalent bonds. But interfacial fracture toughness results reveal that the majority of models are more susceptible to fracture at the interface. Fracture morphology analysis from tensile tests at room temperature and endurance tests at 760 °C/725 MPa confirms that cracks primarily initiate at the carbide/matrix interface. This study suggests that introducing Ta atoms could improve interface strength, as Ta-rich carbides reduce interfacial energy while increasing elastic energy, resulting in the formation of skeletal structures. The relationship between Hf-rich and Ta-rich carbides and their respective morphology was investigated. The findings provide insights into the failure mechanisms of carbide/matrix interface and offer theoretical guidance for enhancing interface strength in superalloy applications.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":null,"pages":null},"PeriodicalIF":3.8,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142310778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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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