The synthesis of high-quality heteroepitaxial diamond films on iridium composite substrates is a critical step toward advancing diamond for electronic and optical applications.Microwave plasma chemical vapor depositio...The synthesis of high-quality heteroepitaxial diamond films on iridium composite substrates is a critical step toward advancing diamond for electronic and optical applications.Microwave plasma chemical vapor deposition,combined with in situ optical emission spectroscopy,enables precise control over growth modes through plasma parameter tuning.In this study,we examine how methane concentration,microwave power,and gas pressure influence plasma species and,consequently,the growth modes of heteroepitaxial diamond by optical emission spectroscopy and scanning electron microscope.At low nucleation densities,increased methane concentrations promote the transition from faceted polyhedral to ballas structures,driven by elevated C_(2) radical concentrations in the plasma.Conversely,at higher nucleation densities,gas pressure,and substrate temperature dominate growth mode determination,leading to diverse morphologies,such as planar,polycrystalline,octahedral,and step-flow growth.These findings elucidate the interplay among plasma species,growth parameters,and growth mode,offering critical insights for optimizing growth conditions and preparing heteroepitaxial diamond films in a specific growth mode.展开更多
The nucleation and transition sequences of topologically close-packed(TCP)phases in a Re-containing Ni-based single crystal superalloy were systematically investigated using in-situ transmission electron microscopy(TE...The nucleation and transition sequences of topologically close-packed(TCP)phases in a Re-containing Ni-based single crystal superalloy were systematically investigated using in-situ transmission electron microscopy(TEM)and three-dimensional atom probe technology(3D-APT).During the initial stage of heat-exposure at 1100℃,the TCP phase forming elements(Re,Co,Cr,etc.)segregated at theγ/γin-terface near theγmatrix side to provide the concentration undulations for the nucleation sites of TCP phases,following which theσand P phase coherently nucleated along the(111)γand(022)γplanes from theγ/γinterface near theγmatrix side,respectively.With prolonged heat-exposure time,transitions fromσphase to P phase,σphase toμphase,and P phase toμphase occurred.Besides,the orientation relationships of TCP phase intergrowth structures indicated that the P phase grew along the(¯101)σplane of theσphase by co-lattice precipitation,meanwhile,theμphase grew with smaller lattice misfits along the(0¯40)σplane of theσphase and the(400)P plane of the P phase.Additionally,the result by first-principles calculation evidenced that theμphase had the lowest system energy to make the transition ofσphase and P phase toμphases inevitable,therefore,the TCP phase ultimately existed as the most stableμphase.Finally,the transition sequences of TCP phase during heat-exposure could be summarized into three types:γmatrix→σ→μ,γmatrix→P→μ,andγmatrix→σ→P→μ.展开更多
A new insight into the microstructural stability was proposed in Ni-based single crystal superalloys with Ru addition,and the element segregation behavior atγ/γ′interface was investigated by three-dimensional atom ...A new insight into the microstructural stability was proposed in Ni-based single crystal superalloys with Ru addition,and the element segregation behavior atγ/γ′interface was investigated by three-dimensional atom probe technology(3D-APT).After standard heat treatment,it was found that Ru addition barely altered the element partitioning coefficient betweenγmatrix andγ′phase,and no element-segregation layer was observed atγ/γ′interface.During the heat exposure at 1100°C,Ru addition obviously promoted the rafting of theγ′precipitates and inhibited the precipitation of topological close-packed(TCP)phases.It was more important that an element-segregation layer containing Re,Co,and Cr was formed in theγmatrix close to theγ/γ′interface due to an“uphill diffusion”effect,and its concentration was obviously reduced after Ru addition.Finally,the microstructural stability based on the element segregation behavior atγ/γ′interface was discussed.This element-segregation layer increased theγ/γ′interfacial energy by increasing the absolute value of the lattice misfit ofγ/γ′interface to promote the rafting of theγ′precipitates after Ru addition.On the other hand,the decrease of the segregation concentration of Re,Co,and Cr elements as TCP phase-forming elements near theγ/γ′interface due to a“reverse partitioning”effect inhibits the precipitation of TCP phases in Ni-based single crystal superalloys after Ru addition.展开更多
Computed tomography(CT)examination is the major measure for detecting and diagnosis of foreign bodies in human body.Although CT has high sensitivity in diagnosis of foreign body,some interference factors may still lea...Computed tomography(CT)examination is the major measure for detecting and diagnosis of foreign bodies in human body.Although CT has high sensitivity in diagnosis of foreign body,some interference factors may still lead to missed diagnosis or misdiagnosis.Here we report a rare case that a bamboo stick accidentally pierced into the left chest of a young man who was drunk and unware of this hurt.The patient experienced cough,chest pain,fever,hemoptysis,and was misdiagnosed as primary and secondary tuberculosis based on chest CT examinations at a local hospital,although no tubercular bacillus detected by sputum smear.He subsequently received anti-tuberculous treatments in the following three years,but no improvement of his symptoms was observed.Until one month before his death,the bamboo stick was detected by spiral CT examination as well as three-dimensional image reconstruction at another hospital.Postmortem examination revealed pneumonia,pulmonary infarction,and abscess as the causes of his death.We analyze the potential reasons of misdiagnosis in this case,aiming to provide reference for the diagnosis and treatment of pulmonary inflammation associated with foreign body in the future.展开更多
As an ultra-wide bandgap semiconductor,diamond garners significant interest due to its exceptional physical properties^([1–3]).These superior characteristics make diamonds highly promising for applications in power e...As an ultra-wide bandgap semiconductor,diamond garners significant interest due to its exceptional physical properties^([1–3]).These superior characteristics make diamonds highly promising for applications in power electronics^([4]),deep-ultraviolet detectors^([5]),high-energy particle detectors^([6]),and quantum devices based on color centers^([7]).展开更多
The creep anisotropy of Ni-based single crystal superalloys was studied at 750 °C/750 MPa. Transmission electron microscopy (TEM) observations showed that stacking faults and micro-twins were the typical dislocat...The creep anisotropy of Ni-based single crystal superalloys was studied at 750 °C/750 MPa. Transmission electron microscopy (TEM) observations showed that stacking faults and micro-twins were the typical dislocation configurations, which all originated from the activity of {111} 〈112〉 slip systems. Then, the orientation rotation caused by the activity of the main {111} 〈112〉 slip system would accelerate the specimen fracturing in shear fracture mode. Furthermore, the orientation rotation would dominate the creep anisotropy. The orientation rotation would occur during the entire creep process, the greater the degree of rotation, the more severe the asynchrony of rotation, which would result in nonuniform deformation and local stress concentration, and exacerbate the failure of the specimen.展开更多
基金funded by the National Key Research and Development Program of China(Grant No.2022YFB3608602)the National Natural Science Foundation of China(Grant Nos.62404215 and 62574199)Instrument and Equipment Development Project of CAS(Grant No.PTYQ2024TD0003)。
文摘The synthesis of high-quality heteroepitaxial diamond films on iridium composite substrates is a critical step toward advancing diamond for electronic and optical applications.Microwave plasma chemical vapor deposition,combined with in situ optical emission spectroscopy,enables precise control over growth modes through plasma parameter tuning.In this study,we examine how methane concentration,microwave power,and gas pressure influence plasma species and,consequently,the growth modes of heteroepitaxial diamond by optical emission spectroscopy and scanning electron microscope.At low nucleation densities,increased methane concentrations promote the transition from faceted polyhedral to ballas structures,driven by elevated C_(2) radical concentrations in the plasma.Conversely,at higher nucleation densities,gas pressure,and substrate temperature dominate growth mode determination,leading to diverse morphologies,such as planar,polycrystalline,octahedral,and step-flow growth.These findings elucidate the interplay among plasma species,growth parameters,and growth mode,offering critical insights for optimizing growth conditions and preparing heteroepitaxial diamond films in a specific growth mode.
基金supported by the National Natural Science Foundation of China(Nos.51771148,52071263,52031012,and 52322410)the Science Center for Gas Turbine Project(No.P2021-A-IV-001-001)+3 种基金the Key Research and Development Program of Shaanxi Province(No.2023-YBGY-432)the Natural Science Ba-sic Research Plan in Shaanxi Province of China(No.2021JC-13)the Science and Technology Funding Key R&D Industry Foresight and Key Technologies of Jiangsu Province(No.BE2022124)the Re-search Fund of the State Key Laboratory of Solidification Processing(NPU),China(No.2021-QZ-03).
文摘The nucleation and transition sequences of topologically close-packed(TCP)phases in a Re-containing Ni-based single crystal superalloy were systematically investigated using in-situ transmission electron microscopy(TEM)and three-dimensional atom probe technology(3D-APT).During the initial stage of heat-exposure at 1100℃,the TCP phase forming elements(Re,Co,Cr,etc.)segregated at theγ/γin-terface near theγmatrix side to provide the concentration undulations for the nucleation sites of TCP phases,following which theσand P phase coherently nucleated along the(111)γand(022)γplanes from theγ/γinterface near theγmatrix side,respectively.With prolonged heat-exposure time,transitions fromσphase to P phase,σphase toμphase,and P phase toμphase occurred.Besides,the orientation relationships of TCP phase intergrowth structures indicated that the P phase grew along the(¯101)σplane of theσphase by co-lattice precipitation,meanwhile,theμphase grew with smaller lattice misfits along the(0¯40)σplane of theσphase and the(400)P plane of the P phase.Additionally,the result by first-principles calculation evidenced that theμphase had the lowest system energy to make the transition ofσphase and P phase toμphases inevitable,therefore,the TCP phase ultimately existed as the most stableμphase.Finally,the transition sequences of TCP phase during heat-exposure could be summarized into three types:γmatrix→σ→μ,γmatrix→P→μ,andγmatrix→σ→P→μ.
基金funded by the National Science and Technol-ogy Major Project(Nos.2017-VI-0002-0072,2019-VI-0020-0135)the National Natural Science Foundation of China(Nos.51771148,52071263,52031012)+2 种基金the Key Research and Development Program of Shaanxi Province(Nos.2020ZDLGY13-02,2023-YBGY-432)the Natural Science Basic Research Plan in Shaanxi Province of China(No.2021JC-13)the Research Fund of the State Key Labora-tory of Solidification Processing(NPU),China(No.2021-QZ-03).
文摘A new insight into the microstructural stability was proposed in Ni-based single crystal superalloys with Ru addition,and the element segregation behavior atγ/γ′interface was investigated by three-dimensional atom probe technology(3D-APT).After standard heat treatment,it was found that Ru addition barely altered the element partitioning coefficient betweenγmatrix andγ′phase,and no element-segregation layer was observed atγ/γ′interface.During the heat exposure at 1100°C,Ru addition obviously promoted the rafting of theγ′precipitates and inhibited the precipitation of topological close-packed(TCP)phases.It was more important that an element-segregation layer containing Re,Co,and Cr was formed in theγmatrix close to theγ/γ′interface due to an“uphill diffusion”effect,and its concentration was obviously reduced after Ru addition.Finally,the microstructural stability based on the element segregation behavior atγ/γ′interface was discussed.This element-segregation layer increased theγ/γ′interfacial energy by increasing the absolute value of the lattice misfit ofγ/γ′interface to promote the rafting of theγ′precipitates after Ru addition.On the other hand,the decrease of the segregation concentration of Re,Co,and Cr elements as TCP phase-forming elements near theγ/γ′interface due to a“reverse partitioning”effect inhibits the precipitation of TCP phases in Ni-based single crystal superalloys after Ru addition.
文摘Computed tomography(CT)examination is the major measure for detecting and diagnosis of foreign bodies in human body.Although CT has high sensitivity in diagnosis of foreign body,some interference factors may still lead to missed diagnosis or misdiagnosis.Here we report a rare case that a bamboo stick accidentally pierced into the left chest of a young man who was drunk and unware of this hurt.The patient experienced cough,chest pain,fever,hemoptysis,and was misdiagnosed as primary and secondary tuberculosis based on chest CT examinations at a local hospital,although no tubercular bacillus detected by sputum smear.He subsequently received anti-tuberculous treatments in the following three years,but no improvement of his symptoms was observed.Until one month before his death,the bamboo stick was detected by spiral CT examination as well as three-dimensional image reconstruction at another hospital.Postmortem examination revealed pneumonia,pulmonary infarction,and abscess as the causes of his death.We analyze the potential reasons of misdiagnosis in this case,aiming to provide reference for the diagnosis and treatment of pulmonary inflammation associated with foreign body in the future.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFB3608600)the Beijing Municipal Science and Technology Commission(Grant No.Z181100004418009)the National Natural Science Foundation of China(Grant No.61927806)。
文摘As an ultra-wide bandgap semiconductor,diamond garners significant interest due to its exceptional physical properties^([1–3]).These superior characteristics make diamonds highly promising for applications in power electronics^([4]),deep-ultraviolet detectors^([5]),high-energy particle detectors^([6]),and quantum devices based on color centers^([7]).
基金funded by National Natural Science Foundation of China(51771148,52322410,52071263,52031012)Science Center for Gas Turbine Project(P2021-A-IV-001-001)+3 种基金Self-innovation Special Fund Project of Aero Engine Corporation of China(ZZCX-2022-040)The Key Research and Development Program of Shaanxi Province(2023-YBGY-432)Research Fund of the State Key Laboratory of Solidification Processing(NPU),China(2021-QZ-03)Innovation Foundation for Doctor Dissertation of Northwestern Poly-technical University,China(CX2021057)。
文摘The creep anisotropy of Ni-based single crystal superalloys was studied at 750 °C/750 MPa. Transmission electron microscopy (TEM) observations showed that stacking faults and micro-twins were the typical dislocation configurations, which all originated from the activity of {111} 〈112〉 slip systems. Then, the orientation rotation caused by the activity of the main {111} 〈112〉 slip system would accelerate the specimen fracturing in shear fracture mode. Furthermore, the orientation rotation would dominate the creep anisotropy. The orientation rotation would occur during the entire creep process, the greater the degree of rotation, the more severe the asynchrony of rotation, which would result in nonuniform deformation and local stress concentration, and exacerbate the failure of the specimen.
