High Nbβ/γ-TiAl(HNBG)intermetallics and Ni-based superalloy(IN718)were diffusion-bonded using pure Ti foil interlayer under pulse current.The microstructure,element segregation,and mechanical properties of HNBG/Ti/I...High Nbβ/γ-TiAl(HNBG)intermetallics and Ni-based superalloy(IN718)were diffusion-bonded using pure Ti foil interlayer under pulse current.The microstructure,element segregation,and mechanical properties of HNBG/Ti/IN718 joint were investigated.The effect of Ti interlayer on microstructure and mechanical properties of the joint was discussed.The typical microstructure of HNBG/Ti/IN718 joint was HNBG//β/B2,τ_(3)-NiAl_(3)Ti_(2)//α_(2)-Ti_(3)Al//α-Ti+δ-NiTi_(2),β-Ti//δ-NiTi_(2)//β2-(Ni,Fe)Ti//Cr/Fe-richη-Ni_(3)Ti,η-Ni_(3)Ti,α-Cr,δ-Ni_(3)Nb//η-Ni_(3)Ti,γ-Ni,δ-Ni_(3)Nb//IN718.The gaps and Kirkendall voids exhibited a gradual disappearance with increasing bonding temperature.The mechanism of Cr,Fe and Nb elements segregation was that NiTi phase hindered the diffusion of them.The nano-indentation results demonstrated that diffusion zones on IN718 alloy side had higher hardness.The maximum shear strength of the joint(326 MPa)was achieved at bonding parameters of 850℃,20 min and 10 MPa.The fracture occurred in Zones IV and V,and the fracture modes were brittle fracture and cleavage fracture.The introduction of Ti interlayer resulted in improved microstructure and enhanced bonding strength of the joint.展开更多
The fatigue damage behavior of the nanocrystalline Au films on polyimide substrates was investigated.It was found that the very high-cycle fatigue damage resistance of the Au film was significantly enhanced by at leas...The fatigue damage behavior of the nanocrystalline Au films on polyimide substrates was investigated.It was found that the very high-cycle fatigue damage resistance of the Au film was significantly enhanced by at least a factor of~2 in supported loading through adding an ultrathin Ti interlayer at the Au film/polyimide interface.Such a better fatigue damage resistance is mainly ascribed to the effective suppression of voiding at the Au film/polyimide interface through modulation of the Au/Ti interface,and thus the propensity of the cyclic strain localization and grain boundary cracking is reduced.The finding may provide a potential strategy for the design of flexible devices with ultra-long fatigue life.展开更多
A Ti interlayer with thickness about 300 nm was sputtered on Cu microchannels, followed by an ultrasonic seeding with nanodiamond powders. Adherent diamond film with crystalline grains close to thermal equilibrium sha...A Ti interlayer with thickness about 300 nm was sputtered on Cu microchannels, followed by an ultrasonic seeding with nanodiamond powders. Adherent diamond film with crystalline grains close to thermal equilibrium shape was tightly deposited by hot-filament chemical vapor deposition(HF-CVD). The nucleation and growth of diamond were investigated with micro-Raman spectroscope and field emission scanning electron microscope(FE-SEM) with energy dispersive X-ray detector(EDX). Results show that the nucleation density is found to be up to 1010 cm-2. The enhancement of the nucleation kinetics can be attributed to the nanometer rough Ti interlayer surface. An improved absorption of nanodiamond particles is found, which act as starting points for the diamond nucleation during HF-CVD process. Furthermore, finite element simulation was conducted to understand the thermal management properties of prepared diamond/Cu microchannel heat sink.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52071021,51871012)Beijing Natural Science Foundation,China(No.2162024)+1 种基金the Fundamental Research Funds for the Central Universities,China(No.FRF-GF-20-20B)the National Program on Key Basic Research Project of China(No.2011CB605502).
文摘High Nbβ/γ-TiAl(HNBG)intermetallics and Ni-based superalloy(IN718)were diffusion-bonded using pure Ti foil interlayer under pulse current.The microstructure,element segregation,and mechanical properties of HNBG/Ti/IN718 joint were investigated.The effect of Ti interlayer on microstructure and mechanical properties of the joint was discussed.The typical microstructure of HNBG/Ti/IN718 joint was HNBG//β/B2,τ_(3)-NiAl_(3)Ti_(2)//α_(2)-Ti_(3)Al//α-Ti+δ-NiTi_(2),β-Ti//δ-NiTi_(2)//β2-(Ni,Fe)Ti//Cr/Fe-richη-Ni_(3)Ti,η-Ni_(3)Ti,α-Cr,δ-Ni_(3)Nb//η-Ni_(3)Ti,γ-Ni,δ-Ni_(3)Nb//IN718.The gaps and Kirkendall voids exhibited a gradual disappearance with increasing bonding temperature.The mechanism of Cr,Fe and Nb elements segregation was that NiTi phase hindered the diffusion of them.The nano-indentation results demonstrated that diffusion zones on IN718 alloy side had higher hardness.The maximum shear strength of the joint(326 MPa)was achieved at bonding parameters of 850℃,20 min and 10 MPa.The fracture occurred in Zones IV and V,and the fracture modes were brittle fracture and cleavage fracture.The introduction of Ti interlayer resulted in improved microstructure and enhanced bonding strength of the joint.
基金supported by the National Natural Science Foundation of China(NSFC,Grant Nos.52071319,51601198 and 51771207)Foundation for Outstanding Young Scholar sponsored by Institute of Metal Research(IMR),Natural Science Foundation of Liaoning Province of China(20180510025)Foundation for Outstanding Young Scholar sponsored by the Shenyang National Laboratory for Materials Science(L2019F23)。
文摘The fatigue damage behavior of the nanocrystalline Au films on polyimide substrates was investigated.It was found that the very high-cycle fatigue damage resistance of the Au film was significantly enhanced by at least a factor of~2 in supported loading through adding an ultrathin Ti interlayer at the Au film/polyimide interface.Such a better fatigue damage resistance is mainly ascribed to the effective suppression of voiding at the Au film/polyimide interface through modulation of the Au/Ti interface,and thus the propensity of the cyclic strain localization and grain boundary cracking is reduced.The finding may provide a potential strategy for the design of flexible devices with ultra-long fatigue life.
基金Project(21271188) supported by the National Natural Science Foundation of China
文摘A Ti interlayer with thickness about 300 nm was sputtered on Cu microchannels, followed by an ultrasonic seeding with nanodiamond powders. Adherent diamond film with crystalline grains close to thermal equilibrium shape was tightly deposited by hot-filament chemical vapor deposition(HF-CVD). The nucleation and growth of diamond were investigated with micro-Raman spectroscope and field emission scanning electron microscope(FE-SEM) with energy dispersive X-ray detector(EDX). Results show that the nucleation density is found to be up to 1010 cm-2. The enhancement of the nucleation kinetics can be attributed to the nanometer rough Ti interlayer surface. An improved absorption of nanodiamond particles is found, which act as starting points for the diamond nucleation during HF-CVD process. Furthermore, finite element simulation was conducted to understand the thermal management properties of prepared diamond/Cu microchannel heat sink.
