Transient Liquid Phase Diffusion bonding (TLP bonding) is an effective method to achieve excellent joint of DD6, which is a new generation single crystal superalloy to manufacture aero-engine turbine blades. In this p...Transient Liquid Phase Diffusion bonding (TLP bonding) is an effective method to achieve excellent joint of DD6, which is a new generation single crystal superalloy to manufacture aero-engine turbine blades. In this paper, the interlayer alloys for DD6 TLP bonding were designed. The alloy foils with thickness 40 μm ~ 60 μm, width 4 mm were prepared by using a single roller rapid solidification apparatus and the TLP bonding of DD6 was conducted. Then the joint microstructure and alloying elements diffusion behaviors were analyzed. The results indicate that microstructures of interlayer alloys prepared are fine and homogeneous, the melting point range of alloys from 1070°C to 1074°C and their melting temperature interval is merely 20°C, when the chemical composition of alloys are 1.5 ~ 2.0Cr, 3.2 ~ 4.0W, 3.7 ~ 4.5Co, 2.2 ~ 3.0Al, 0.7 ~ 1.0Mo, 3.2B, remain Ni (wt%). When the welding parameters are bonding temperature 1200?C, holding time 8.0 hour and welding pressure 0.3 MPa, the compacted joints obtained and the microstructure of TLP bonding seams were similar to base metal. The bonding joint is composed of weld center zone, isothermal solidification zone and diffusion-affected zone. Within joint, the elements diffusion is sufficient and borides in the diffusion zone are fewer.展开更多
The effect of thermal exposure on the microstructure and creep properties of the Ni-based single crystal superalloy in different test conditions was studied.Long-term exposure was performed at 1,000 ℃ and 1,100 ℃ fo...The effect of thermal exposure on the microstructure and creep properties of the Ni-based single crystal superalloy in different test conditions was studied.Long-term exposure was performed at 1,000 ℃ and 1,100 ℃ for 500 h prior to the creep tests.The creep lifetime is found to be improved after the long-term exposure at 1,000 ℃ for 500 h as a result of the formation of secondary M_(23)C_(6) in the interdendritic region.The coarsening of γ’ precipitates accompanied by the formation of TCP phase lead to the degradation of alloy,which is responsible for the reduction of the creep lifetime of Ni-base single crystal superalloy after long-term exposure at 1,100 ℃ for 500 h.The creep lifetime of 1,000 oC thermally exposed sample under the conditions of 1,093 ℃/137 MPa is lower than that of heat-treated state.Thermal exposure at 1,100 ℃ for 500 h causes the creep lifetime to drop drastically.展开更多
Multifunctional lead-free double perovskites demonstrate remarkable potential towards applications in various fields.Herein,an environmentally-friendly,low-cost,high-throughput Cs_(2)NaFeCl_(6) single crystal with exc...Multifunctional lead-free double perovskites demonstrate remarkable potential towards applications in various fields.Herein,an environmentally-friendly,low-cost,high-throughput Cs_(2)NaFeCl_(6) single crystal with exceedingly high thermal stability is designed and grown.It obtains a cubic lattice system in the temperature range of 80-500 K,accompanied by a completely reversible chromatic variation ranging from yellow to black.Importantly,the intriguing thermochromism is proved to own extremely high reproducibility(over 1000 cycles)without a hysteretic effect,originating from its structural flexibility that including(i)the noteworthy distortion/deformation of[NaCl_(6)]5−and[FeCl_(6)]3−octahedra;(ii)order-disorder arrangement transition of[NaCl_(6)]5−and[FeCl6]3−octahedra as the function of temperature.This study paves the way towards a new class of smart windows and camouflage coatings with an unprecedented colour range based on a Cs_(2)NaFeCl_(6) perovskite.展开更多
Single crystals of R2PdGe6 (R=Pr, Gd and Tb) compounds were grown by the Bi-flux method. Pr2PdGe6 is an antiferromagnetic compound with Neel temperature Tn=15K, in which a field-induced magnetic transition (spin flip)...Single crystals of R2PdGe6 (R=Pr, Gd and Tb) compounds were grown by the Bi-flux method. Pr2PdGe6 is an antiferromagnetic compound with Neel temperature Tn=15K, in which a field-induced magnetic transition (spin flip) occurs when a magnetic field is applied along either a or b axis;a small magnetization and hysteresis loop were observed when a field is applied along c axis. Gd2PdGe6 is a colli near antiferromagnetic compound with Tn=37K along b axis. Tb2PdGe6 is an antiferromagnetic compound with Tn =48 K and its hard magnetization direction is along b axis. The temperature dependences of the resista nee of the entire three compounds prese nt inflection points at the respective Tn-A large resista nee (as well as magnetoresistance) change can be found at the spin flip transition of Pr2 PdGe6, but the change is not obvious at the spin flop transition of Gd2PdGe6.展开更多
文摘Transient Liquid Phase Diffusion bonding (TLP bonding) is an effective method to achieve excellent joint of DD6, which is a new generation single crystal superalloy to manufacture aero-engine turbine blades. In this paper, the interlayer alloys for DD6 TLP bonding were designed. The alloy foils with thickness 40 μm ~ 60 μm, width 4 mm were prepared by using a single roller rapid solidification apparatus and the TLP bonding of DD6 was conducted. Then the joint microstructure and alloying elements diffusion behaviors were analyzed. The results indicate that microstructures of interlayer alloys prepared are fine and homogeneous, the melting point range of alloys from 1070°C to 1074°C and their melting temperature interval is merely 20°C, when the chemical composition of alloys are 1.5 ~ 2.0Cr, 3.2 ~ 4.0W, 3.7 ~ 4.5Co, 2.2 ~ 3.0Al, 0.7 ~ 1.0Mo, 3.2B, remain Ni (wt%). When the welding parameters are bonding temperature 1200?C, holding time 8.0 hour and welding pressure 0.3 MPa, the compacted joints obtained and the microstructure of TLP bonding seams were similar to base metal. The bonding joint is composed of weld center zone, isothermal solidification zone and diffusion-affected zone. Within joint, the elements diffusion is sufficient and borides in the diffusion zone are fewer.
基金funded by the Key Laboratory of Advanced High-temperature Structural Materials for National Defense Science and Technology,China(No:6142903180104)。
文摘The effect of thermal exposure on the microstructure and creep properties of the Ni-based single crystal superalloy in different test conditions was studied.Long-term exposure was performed at 1,000 ℃ and 1,100 ℃ for 500 h prior to the creep tests.The creep lifetime is found to be improved after the long-term exposure at 1,000 ℃ for 500 h as a result of the formation of secondary M_(23)C_(6) in the interdendritic region.The coarsening of γ’ precipitates accompanied by the formation of TCP phase lead to the degradation of alloy,which is responsible for the reduction of the creep lifetime of Ni-base single crystal superalloy after long-term exposure at 1,100 ℃ for 500 h.The creep lifetime of 1,000 oC thermally exposed sample under the conditions of 1,093 ℃/137 MPa is lower than that of heat-treated state.Thermal exposure at 1,100 ℃ for 500 h causes the creep lifetime to drop drastically.
基金The research was funded by the National Natural Science Foundation of China(No.51802120,51872126,22075103,51672111)Guangdong Basic and Applied Basic Research Foundation for Distinguished Young Scholar(No.2019B151502030)+7 种基金Natural Science Foundation of Guangdong Province(No.2018030310181)the Science and Technology Plan Project of Guangzhou(No.202002030159)Guangdong Basic and Applied Basic Research Foundation for Young Scholar(No.2020A1515111057)‘100 Talents Program of Hebei Province’(No.E2014100008)the Fundamental Research Funds for the Central Universities(No.21619406)X.Y.thanks for the Special Funds for the Cultivation of Guangdong College Students'Scientific and Technological Innovation("Climbing Program"Special Funds)(No.pdjh2019a0055)J.Fan also thanks for the project support for"Young Top talents"in the Pearl River Talent Project of Guangdong Province(2017GC010424)the Guangdong Provincial Innovation and Entrepreneurship Project(grant 2016ZT06D081).
文摘Multifunctional lead-free double perovskites demonstrate remarkable potential towards applications in various fields.Herein,an environmentally-friendly,low-cost,high-throughput Cs_(2)NaFeCl_(6) single crystal with exceedingly high thermal stability is designed and grown.It obtains a cubic lattice system in the temperature range of 80-500 K,accompanied by a completely reversible chromatic variation ranging from yellow to black.Importantly,the intriguing thermochromism is proved to own extremely high reproducibility(over 1000 cycles)without a hysteretic effect,originating from its structural flexibility that including(i)the noteworthy distortion/deformation of[NaCl_(6)]5−and[FeCl_(6)]3−octahedra;(ii)order-disorder arrangement transition of[NaCl_(6)]5−and[FeCl6]3−octahedra as the function of temperature.This study paves the way towards a new class of smart windows and camouflage coatings with an unprecedented colour range based on a Cs_(2)NaFeCl_(6) perovskite.
基金supported financially by the National Natural Science Foundation of China (Nos. 51671192 and 51531008)the Chinese Academy of Sciences (No. KJZD-EW-M05)the National Key Research and Development Program of China (No. 2017YFB0702701)
文摘Single crystals of R2PdGe6 (R=Pr, Gd and Tb) compounds were grown by the Bi-flux method. Pr2PdGe6 is an antiferromagnetic compound with Neel temperature Tn=15K, in which a field-induced magnetic transition (spin flip) occurs when a magnetic field is applied along either a or b axis;a small magnetization and hysteresis loop were observed when a field is applied along c axis. Gd2PdGe6 is a colli near antiferromagnetic compound with Tn=37K along b axis. Tb2PdGe6 is an antiferromagnetic compound with Tn =48 K and its hard magnetization direction is along b axis. The temperature dependences of the resista nee of the entire three compounds prese nt inflection points at the respective Tn-A large resista nee (as well as magnetoresistance) change can be found at the spin flip transition of Pr2 PdGe6, but the change is not obvious at the spin flop transition of Gd2PdGe6.
