Six-layered W-TiC/Cu functionally graded materials were fabricated by resistance sintering under ultra-high pressure and exposed in the edge plasma of HT-7 tokamak. Microstruc- ture morphologies show that the TiC part...Six-layered W-TiC/Cu functionally graded materials were fabricated by resistance sintering under ultra-high pressure and exposed in the edge plasma of HT-7 tokamak. Microstruc- ture morphologies show that the TiC particles distribute homogeneously in the W matrix, strength- ening the grain boundary, while gradient layers provide a good compositional transition from W- TiC to Cu. After about 360 shots in the HT-7 tokamak, clear surface modification can be observed after plasma exposure, and the addition of nano TiC particles is beneficial to the improvement of plasma loads resistance of W.展开更多
Novel ZTA/Al 2O 3 SiC w TiC polyphase ceramics were fabricated by hot pressing techniques. Phase transformation toughening, particle dispersion and whisker reinforcement have obviously superposed strengthening an...Novel ZTA/Al 2O 3 SiC w TiC polyphase ceramics were fabricated by hot pressing techniques. Phase transformation toughening, particle dispersion and whisker reinforcement have obviously superposed strengthening and toughening effects. It is observed that ZTA 20SiC w 20TiC has better comprehensive mechanical properties compared with Al 2O 3 20SiC w 20TiC. For the optimum processing, the ZTA 20SiC w 20TiC exhibited a flexural strength of 567MPa, a fracture toughness of 6.3MPa·m 0.5 , a hardness of HRA93.6 and a relative density of ≥99.6%. The tensile stress in matrix introduced by SiC whisker and TiC could be relaxed by the compress stress produced by tetragonal zirconia(ZrO 2(t)) transformation. TiC formed a continuous skeleton which prevented the grain growth of the matrix. The grain sizes of the matrix became finer with increasing TiC. The major fracture mode of the matrix was transcrystalline cleavage rupture.展开更多
In order to improve the homogeneous distribution of the TiC particles and facilitate the TiC particles to distribute in the tungsten grain interiors,two kinds of TiCdoped tungsten precursors with a core-shell structur...In order to improve the homogeneous distribution of the TiC particles and facilitate the TiC particles to distribute in the tungsten grain interiors,two kinds of TiCdoped tungsten precursors with a core-shell structure were prepared by an improved wet chemical method at different reaction temperature conditions.Consequently,fine platelike precursor(200-400 nm)and flower-like precursor(approximately 1.25μm)are obtained.After reduction and sintering,the microstructures of the samples were characterized by scanning electron microscopy and transmission electron microscopy.In the sample sintered from the platelike precursor,TiC particles with sizes in the range of40-300 nm and an average size of approximately 80 nm were uniformly distributed in the tungsten matrix with a high share in the grain interiors.However,in the sample sintered from the flower-like precursor,the TiC particles with sizes in the range of 50-700 nm are significantly aggregated and non-uniformly distributed in the tungsten matrix.As a result,the sample sintered from the plate-like precursor achieves higher mechanical properties and a much narrower range of bending strength values than that sintered from the flower-like precursor.The average bending strength of the sample sintered from the plate-like precursor is 655 MPa,which is higher than that of the sample sintered from the flower-like precursor(524 MPa).Different reaction mechanisms and dispersing stabilities of the TiC particles at different temperature conditions should be accounted for the differences between the two samples.展开更多
Considering that tungsten(W)materials served as the plasma-facing material in the fusion reactor would be exposed to edge-localized modes(ELMs)-like thermal shock loading accompanied with He-ion irradiation,the W-TiC ...Considering that tungsten(W)materials served as the plasma-facing material in the fusion reactor would be exposed to edge-localized modes(ELMs)-like thermal shock loading accompanied with He-ion irradiation,the W-TiC composite produced with a wet-chemical method was conducted by the dual effects from the laser beam thermal shock first and He-ion irradia-tion later in this work.The microstructure changes of the W-TiC composite before and after two tests were characterized by scanning electron microscopy or transmission electron microscopy.After the laser beam thermal shock test,there was an obvious interface on the exposed surface of the W-TiC composite.Several main cracks and melting areas could be found nearby the interface and center,respectively.Furthermore,a mixture of tungsten oxide and TiC was easy to aggregate and form into circle areas surrounding the melting area.The thermal shock tested that W-TiC composite was then subjected to the He-ion irradiation.The typical features of fuzz structures could be detected on the surface of the W-TiC composite apart from the center of the melting area.Notably,several nano-sized He bubbles deeply distributed at grain boundaries in the melting area,owing to the grain boundary functioning as the free path for He diffusion.展开更多
基金supported by National Natural Science Foundation of China (No.11175205)
文摘Six-layered W-TiC/Cu functionally graded materials were fabricated by resistance sintering under ultra-high pressure and exposed in the edge plasma of HT-7 tokamak. Microstruc- ture morphologies show that the TiC particles distribute homogeneously in the W matrix, strength- ening the grain boundary, while gradient layers provide a good compositional transition from W- TiC to Cu. After about 360 shots in the HT-7 tokamak, clear surface modification can be observed after plasma exposure, and the addition of nano TiC particles is beneficial to the improvement of plasma loads resistance of W.
文摘Novel ZTA/Al 2O 3 SiC w TiC polyphase ceramics were fabricated by hot pressing techniques. Phase transformation toughening, particle dispersion and whisker reinforcement have obviously superposed strengthening and toughening effects. It is observed that ZTA 20SiC w 20TiC has better comprehensive mechanical properties compared with Al 2O 3 20SiC w 20TiC. For the optimum processing, the ZTA 20SiC w 20TiC exhibited a flexural strength of 567MPa, a fracture toughness of 6.3MPa·m 0.5 , a hardness of HRA93.6 and a relative density of ≥99.6%. The tensile stress in matrix introduced by SiC whisker and TiC could be relaxed by the compress stress produced by tetragonal zirconia(ZrO 2(t)) transformation. TiC formed a continuous skeleton which prevented the grain growth of the matrix. The grain sizes of the matrix became finer with increasing TiC. The major fracture mode of the matrix was transcrystalline cleavage rupture.
基金financially supported by the ITER-National Magnetic Confinement Fusion Program(No.2014GB123000)。
文摘In order to improve the homogeneous distribution of the TiC particles and facilitate the TiC particles to distribute in the tungsten grain interiors,two kinds of TiCdoped tungsten precursors with a core-shell structure were prepared by an improved wet chemical method at different reaction temperature conditions.Consequently,fine platelike precursor(200-400 nm)and flower-like precursor(approximately 1.25μm)are obtained.After reduction and sintering,the microstructures of the samples were characterized by scanning electron microscopy and transmission electron microscopy.In the sample sintered from the platelike precursor,TiC particles with sizes in the range of40-300 nm and an average size of approximately 80 nm were uniformly distributed in the tungsten matrix with a high share in the grain interiors.However,in the sample sintered from the flower-like precursor,the TiC particles with sizes in the range of 50-700 nm are significantly aggregated and non-uniformly distributed in the tungsten matrix.As a result,the sample sintered from the plate-like precursor achieves higher mechanical properties and a much narrower range of bending strength values than that sintered from the flower-like precursor.The average bending strength of the sample sintered from the plate-like precursor is 655 MPa,which is higher than that of the sample sintered from the flower-like precursor(524 MPa).Different reaction mechanisms and dispersing stabilities of the TiC particles at different temperature conditions should be accounted for the differences between the two samples.
基金the National Natural Science Foundation of China(Grant No.51574101)the Fundamental Research Funds for the Central Universities(Grant Nos.PA2018GDQT0010,PA2019GDZC0096,JZ2019HGTA0040)+2 种基金the Foundation of Laboratory of Nonferrous Metal Material and Processing Engineering of Anhui Province(15CZS08031)the Natural Science Foundation of Anhui Province(Grant Nos.201904b11020034,1908085ME115)the Foundation of Laboratory of Nonferrous Metal Material and Processing Engineering of Anhui Province,the Open Foundation of Key Laboratory of Advanced Functional Materials,Devices of Anhui Province and Double First Class enhancing independent innovation and social service capabilities of Hefei University of Technology(Grant No.45000-411104/011).
文摘Considering that tungsten(W)materials served as the plasma-facing material in the fusion reactor would be exposed to edge-localized modes(ELMs)-like thermal shock loading accompanied with He-ion irradiation,the W-TiC composite produced with a wet-chemical method was conducted by the dual effects from the laser beam thermal shock first and He-ion irradia-tion later in this work.The microstructure changes of the W-TiC composite before and after two tests were characterized by scanning electron microscopy or transmission electron microscopy.After the laser beam thermal shock test,there was an obvious interface on the exposed surface of the W-TiC composite.Several main cracks and melting areas could be found nearby the interface and center,respectively.Furthermore,a mixture of tungsten oxide and TiC was easy to aggregate and form into circle areas surrounding the melting area.The thermal shock tested that W-TiC composite was then subjected to the He-ion irradiation.The typical features of fuzz structures could be detected on the surface of the W-TiC composite apart from the center of the melting area.Notably,several nano-sized He bubbles deeply distributed at grain boundaries in the melting area,owing to the grain boundary functioning as the free path for He diffusion.
