Over the past decades,considerable efforts have been made in the commercial application of bulk metallic glasses(BMGs).Despite great challenges faced by the industrial players,significant progress has been achieved,an...Over the past decades,considerable efforts have been made in the commercial application of bulk metallic glasses(BMGs).Despite great challenges faced by the industrial players,significant progress has been achieved,and millions of commercial products for various kinds of applications have been shipped around the world.Here in this paper,we shall present the alloys suitable for the actual products in the application and discuss the merits of the processing technique of BMGs over the existing processing techniques and materials.Most importantly we demonstrate the typical examples of products over the past few years.Finally,future directions of the industrialization of BMGs are also discussed.展开更多
In order to improve the oxidation and wear resistance of blades tip of titanium alloys as well as the sealing performance of the gas turbine engine,a Ni/cBN abrasive coating was prepared on titanium alloys through com...In order to improve the oxidation and wear resistance of blades tip of titanium alloys as well as the sealing performance of the gas turbine engine,a Ni/cBN abrasive coating was prepared on titanium alloys through composite electroplating.Oxidation,mechanical and tribological properties of the abrasive coating were investigated.Furthermore,the effect of the oxidation on the mechanical and tribological properties was also evaluated.Oxidation results revealed that the abrasive coating underwent slight oxidation within 700℃.Meanwhile,some intermetallic compounds,Ni3Ti,NiTi and NiTi2,were formed at the coating/substrate interface during oxidation.Due to the pinning effect of cBN particles and the different thermal expansion coefficients of the coating and substrate,the coating/substrate interface was cracked after oxidation at 700℃.Tensile results showed that the presence of coating reduced the strength of the alloy significantly at room temperature,while only marginal variations of the strength of the coated and uncoated specimens at elevated temperatures.Besides,the wear tests indicated that the coating had the excellent cutting ability and wear resistance,which can effectively protect the blades tip of titanium alloys.As the temperature increased,the wear resistance decreased due to the decrease in the mechanical properties of the Ni/cBN coating.展开更多
The influence of the bilayer number on the microstructure,mechanical properties,adhesion strength and tribological behaviors of the WB_(2)/Cr multilayer films was systematically investigated in the present study.Five ...The influence of the bilayer number on the microstructure,mechanical properties,adhesion strength and tribological behaviors of the WB_(2)/Cr multilayer films was systematically investigated in the present study.Five groups of WB_(2)/Cr films with the same modulation ratio were synthesized by magnetron sputtering technique.The crystalline structure of the films was determined by X-ray diffraction.The morphologies and the microstructure of the films were observed by scanning electron microscopy,atomic force microscopy and transmission electron microscopy.Furthermore,Nano indenter,scratch tester and ball-on-disc tribometer were used to evaluate the mechanical and tribological properties.As bilayer numbers varied from 5 to 40,the hardness increased first and then decreased with the maximum hardness of 33.9 GPa when the bilayer number is 30.The H/E^(*)and H^(3)/E^(*2)values calculated to evaluate the fracture toughness showed the similar changing trend with hardness.The adhesion strength reached the maximum of 67 N when the bilayer number is 30.The surface roughness and friction coefficient decreased with increasing bilayer number.The wear mechanism was also investigated,and the results suggested that the multilayer film with bilayer number of 30 exhibited the best wear resistance(1.78×10^(–7)mm^(3)/Nm),benefiting from the contribution of high hardness,fracture toughness and adhesion strength.展开更多
The cosmic-ray(CR)electrons and positrons in space are of considerable significance for studying the origin and propagation of CRs.The satellite-borne detector Dark Matter Particle Explorer(DAMPE)has been used to meas...The cosmic-ray(CR)electrons and positrons in space are of considerable significance for studying the origin and propagation of CRs.The satellite-borne detector Dark Matter Particle Explorer(DAMPE)has been used to measure the separate electron and positron spectra,as well as the positron fraction.In this study,the Earth's magnetic field is used to distinguish CR electrons and positrons,as the DAMPE detector does not carry an onboard magnet.The energy for the measurements ranges from 10 to 20 GeV,which is currently limited at high energy by the zenith-pointing orientation of DAMPE.The results are consistent with previous measurements based on the magnetic spectrometer by AMS-02 and PAMELA,whereas the results of Fermi-LAT appear to be systematically shifted to larger values.展开更多
Sweeping jet actuator(SJA)has been widely applied for activeflow control in openflows.In this paper,the SJA character in compressor cascade and its performance for separation control in innerflows are discussed.Time-a...Sweeping jet actuator(SJA)has been widely applied for activeflow control in openflows.In this paper,the SJA character in compressor cascade and its performance for separation control in innerflows are discussed.Time-averaged and transientflowfield measurement,together with visualization methods are utilized.It is found that endwall effects are important for both SJA behaviors and SJA performance for separation control in compressor cascades.There is a maximum of 12.7%total pressure loss reduction with SJA placed near the separation position,close to the endwall and under appropriateflowrate.The characteristic frequencies in theflowfield contribute to the capture of influence regions of vortices and excitation jets.Two concentrated shedding vortices and SJA jets impact region helped to judge that SJA energizes low momentumfluids in a large region and matches the high loss core well.To be concrete,theflow separation control mechanism of SJA lies on the interruption of the blade suction surface boundary layer development and the restriction of the lifting of the boundary layer from end-wall towards blade suction surface.展开更多
基金financial support from the Shenyang National Laboratory for Materials Science,Institute of Metal Research。
文摘Over the past decades,considerable efforts have been made in the commercial application of bulk metallic glasses(BMGs).Despite great challenges faced by the industrial players,significant progress has been achieved,and millions of commercial products for various kinds of applications have been shipped around the world.Here in this paper,we shall present the alloys suitable for the actual products in the application and discuss the merits of the processing technique of BMGs over the existing processing techniques and materials.Most importantly we demonstrate the typical examples of products over the past few years.Finally,future directions of the industrialization of BMGs are also discussed.
基金supported by the National Science and Technology Major Project(No.2017-Ⅶ-0012-0108)the Natural Science Foundation of China(No.51701157)。
文摘In order to improve the oxidation and wear resistance of blades tip of titanium alloys as well as the sealing performance of the gas turbine engine,a Ni/cBN abrasive coating was prepared on titanium alloys through composite electroplating.Oxidation,mechanical and tribological properties of the abrasive coating were investigated.Furthermore,the effect of the oxidation on the mechanical and tribological properties was also evaluated.Oxidation results revealed that the abrasive coating underwent slight oxidation within 700℃.Meanwhile,some intermetallic compounds,Ni3Ti,NiTi and NiTi2,were formed at the coating/substrate interface during oxidation.Due to the pinning effect of cBN particles and the different thermal expansion coefficients of the coating and substrate,the coating/substrate interface was cracked after oxidation at 700℃.Tensile results showed that the presence of coating reduced the strength of the alloy significantly at room temperature,while only marginal variations of the strength of the coated and uncoated specimens at elevated temperatures.Besides,the wear tests indicated that the coating had the excellent cutting ability and wear resistance,which can effectively protect the blades tip of titanium alloys.As the temperature increased,the wear resistance decreased due to the decrease in the mechanical properties of the Ni/cBN coating.
基金supported by the National Natural Science Foundation of China(No.51701157)。
文摘The influence of the bilayer number on the microstructure,mechanical properties,adhesion strength and tribological behaviors of the WB_(2)/Cr multilayer films was systematically investigated in the present study.Five groups of WB_(2)/Cr films with the same modulation ratio were synthesized by magnetron sputtering technique.The crystalline structure of the films was determined by X-ray diffraction.The morphologies and the microstructure of the films were observed by scanning electron microscopy,atomic force microscopy and transmission electron microscopy.Furthermore,Nano indenter,scratch tester and ball-on-disc tribometer were used to evaluate the mechanical and tribological properties.As bilayer numbers varied from 5 to 40,the hardness increased first and then decreased with the maximum hardness of 33.9 GPa when the bilayer number is 30.The H/E^(*)and H^(3)/E^(*2)values calculated to evaluate the fracture toughness showed the similar changing trend with hardness.The adhesion strength reached the maximum of 67 N when the bilayer number is 30.The surface roughness and friction coefficient decreased with increasing bilayer number.The wear mechanism was also investigated,and the results suggested that the multilayer film with bilayer number of 30 exhibited the best wear resistance(1.78×10^(–7)mm^(3)/Nm),benefiting from the contribution of high hardness,fracture toughness and adhesion strength.
基金supported by the National Key Research and Development Program of China(No.2022YFF0503303)the National Natural Science Foundation of China(Nos.12220101003,12275266,12003076,12022503,12103094 and U2031149)+8 种基金Outstanding Youth Science Foundation of NSFC(No.12022503)the Project for Young Scientists in Basic Research of the Chinese Academy of Sciences(No.YSBR-061)the Strategic Priority Program on Space Science of Chinese Academy of Sciences(No.E02212A02S)the Youth Innovation Promotion Association of CAS(No.2021450)the Young Elite Scientists Sponsorship Program by CAST(No.YESS20220197)the New Cornerstone Science Foundation through the XPLORER PRIZEthe Program for Innovative Talents and Entrepreneur in Jiangsu.In Europesupported by the Swiss National Science Foundation(SNSF),Switzerland,the National Institute for Nuclear Physics(INFN),Italythe European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation programme(No.851103).
文摘The cosmic-ray(CR)electrons and positrons in space are of considerable significance for studying the origin and propagation of CRs.The satellite-borne detector Dark Matter Particle Explorer(DAMPE)has been used to measure the separate electron and positron spectra,as well as the positron fraction.In this study,the Earth's magnetic field is used to distinguish CR electrons and positrons,as the DAMPE detector does not carry an onboard magnet.The energy for the measurements ranges from 10 to 20 GeV,which is currently limited at high energy by the zenith-pointing orientation of DAMPE.The results are consistent with previous measurements based on the magnetic spectrometer by AMS-02 and PAMELA,whereas the results of Fermi-LAT appear to be systematically shifted to larger values.
基金supported by the National Natural Science Foundation of China (Grant Nos.52076052 and U2233207).
文摘Sweeping jet actuator(SJA)has been widely applied for activeflow control in openflows.In this paper,the SJA character in compressor cascade and its performance for separation control in innerflows are discussed.Time-averaged and transientflowfield measurement,together with visualization methods are utilized.It is found that endwall effects are important for both SJA behaviors and SJA performance for separation control in compressor cascades.There is a maximum of 12.7%total pressure loss reduction with SJA placed near the separation position,close to the endwall and under appropriateflowrate.The characteristic frequencies in theflowfield contribute to the capture of influence regions of vortices and excitation jets.Two concentrated shedding vortices and SJA jets impact region helped to judge that SJA energizes low momentumfluids in a large region and matches the high loss core well.To be concrete,theflow separation control mechanism of SJA lies on the interruption of the blade suction surface boundary layer development and the restriction of the lifting of the boundary layer from end-wall towards blade suction surface.
