Tensile and fracture behaviors of sandwich-structured composites consisting of a Fe-based amorphous layer with a constant thickness and ultrafine-grained Ni layers with different thicknesses were investigated. The res...Tensile and fracture behaviors of sandwich-structured composites consisting of a Fe-based amorphous layer with a constant thickness and ultrafine-grained Ni layers with different thicknesses were investigated. The results indicate that the initiation and the stable propagation of the shear band in the amorphous layer was dominated by the Ni layers due to their strong constraint role. The catastrophic fracture of the amorphous layer was postponed in the sandwich composites through properly increasing the constrained Ni layer thickness, which effectively decreased the shear stress on the shear fracture planes of the amorphous layer, and thus led to stable propagation of the primary SB characterized by the increase in the smooth region size of the shear band.展开更多
Implementation of novelγ/γ'Co-based superalloys with higher strength and improved creep durability is a challenging task for researchers.The lack of atomic-level understanding of plastic deformation behavior has...Implementation of novelγ/γ'Co-based superalloys with higher strength and improved creep durability is a challenging task for researchers.The lack of atomic-level understanding of plastic deformation behavior has seriously limited the exploration of the full capacity of Co-based alloys.We put forward a comprehensive study of generalized stacking fault energies by first principles to explore the effect of Ni and Al/W on the plastic deformation mechanism ofγ'precipitates in Co-based superalloys.It is found that alloying Ni and adjusting Al/W obviously change the dislocation glide and twinning nucleation in theγ'precipitates by altering the stable fault energies and the unstable fault energy barriers.Excessive addition of either Ni or W deteriorates the strength even the stability of alloys.The ratio of effective planar fault energy(ΔEp)bridges intrinsic energy barriers and various deformation mechanisms of superalloys at elevated temperatures.Except for alloying effects,the grain orientation also significantly governs the operation of the plastic deformation of superalloys.Our theoretical results agree with the available measurements and well capture the observed phenomena in experiments.展开更多
Purpose CMOS pixel sensor has become extremely attractive for future high-performance tracking devices.It has been proposed for the vertex detector at the Circular Electron Positron Collider,which will allow precision...Purpose CMOS pixel sensor has become extremely attractive for future high-performance tracking devices.It has been proposed for the vertex detector at the Circular Electron Positron Collider,which will allow precision measurements of the properties of the Higgs boson.To meet the stringent requirements for low power consumption,it is necessary to optimize the pixel sensor diode geometry to reach a high charge-over-capacitance ratio that allows reduction in analog power consumption.Methods Collection electrode size and footprint are two critical elements in sensor diode geometry and have deciding impacts on the charge collection performance.A prototype CMOS pixel sensor,named JadePix-1,has been developed with pixel sectors implemented with different electrode sizes and footprints,and its charge collection performance has been characterized with radioactive sources.Results Charge-to-voltage conversion gains for pixel sectors under test have been calibrated with low-energy X-rays.Characterization results have been obtained for equivalent noise charge(below 10e−),charge collection efficiency(around 40%),charge-over-capacitance ratio(above 0.015 V)and signal-to-noise ratio(higher than 55).Conclusion Small collection electrode size and large footprint are preferred to achieve high charge-over-capacitance ratio that promises low analog power consumption.Ongoing studies on sensor performance before and after irradiation,combined with this work,will conclude the diode geometry optimization.展开更多
基金supported by the National Natural Science Foundation of China(NSFC,Grant Nos.51571199 and 51671050)supported by NSFC(Grant No.51601198)
文摘Tensile and fracture behaviors of sandwich-structured composites consisting of a Fe-based amorphous layer with a constant thickness and ultrafine-grained Ni layers with different thicknesses were investigated. The results indicate that the initiation and the stable propagation of the shear band in the amorphous layer was dominated by the Ni layers due to their strong constraint role. The catastrophic fracture of the amorphous layer was postponed in the sandwich composites through properly increasing the constrained Ni layer thickness, which effectively decreased the shear stress on the shear fracture planes of the amorphous layer, and thus led to stable propagation of the primary SB characterized by the increase in the smooth region size of the shear band.
基金financially supported by the National Natural Science Foundation of China(No.51601161)the Youth Innovation Fund Project of Xiamen(No.3502Z20206057)the Natural Science Foundation of Fujian Province of China(No.2020J01051)。
文摘Implementation of novelγ/γ'Co-based superalloys with higher strength and improved creep durability is a challenging task for researchers.The lack of atomic-level understanding of plastic deformation behavior has seriously limited the exploration of the full capacity of Co-based alloys.We put forward a comprehensive study of generalized stacking fault energies by first principles to explore the effect of Ni and Al/W on the plastic deformation mechanism ofγ'precipitates in Co-based superalloys.It is found that alloying Ni and adjusting Al/W obviously change the dislocation glide and twinning nucleation in theγ'precipitates by altering the stable fault energies and the unstable fault energy barriers.Excessive addition of either Ni or W deteriorates the strength even the stability of alloys.The ratio of effective planar fault energy(ΔEp)bridges intrinsic energy barriers and various deformation mechanisms of superalloys at elevated temperatures.Except for alloying effects,the grain orientation also significantly governs the operation of the plastic deformation of superalloys.Our theoretical results agree with the available measurements and well capture the observed phenomena in experiments.
基金the National Natural Science Foundation of China(Nos.11505207,11573028)the State Key Laboratory of Particle Detection and Electronics,the CAS Center for Excellence in Particle Physics(CCEPP)and the IHEP Innovation Fund and the International Partnership Program of Chinese Academy of Sciences.
文摘Purpose CMOS pixel sensor has become extremely attractive for future high-performance tracking devices.It has been proposed for the vertex detector at the Circular Electron Positron Collider,which will allow precision measurements of the properties of the Higgs boson.To meet the stringent requirements for low power consumption,it is necessary to optimize the pixel sensor diode geometry to reach a high charge-over-capacitance ratio that allows reduction in analog power consumption.Methods Collection electrode size and footprint are two critical elements in sensor diode geometry and have deciding impacts on the charge collection performance.A prototype CMOS pixel sensor,named JadePix-1,has been developed with pixel sectors implemented with different electrode sizes and footprints,and its charge collection performance has been characterized with radioactive sources.Results Charge-to-voltage conversion gains for pixel sectors under test have been calibrated with low-energy X-rays.Characterization results have been obtained for equivalent noise charge(below 10e−),charge collection efficiency(around 40%),charge-over-capacitance ratio(above 0.015 V)and signal-to-noise ratio(higher than 55).Conclusion Small collection electrode size and large footprint are preferred to achieve high charge-over-capacitance ratio that promises low analog power consumption.Ongoing studies on sensor performance before and after irradiation,combined with this work,will conclude the diode geometry optimization.
