WC-Co hard metal was furnace brazed by Ag-Cu-Zn+Ni/Mn filler alloy using a tube furnace under high-purity argon at730°C.The influence of brazing time and gap size of joints was studied.The results revealed the ma...WC-Co hard metal was furnace brazed by Ag-Cu-Zn+Ni/Mn filler alloy using a tube furnace under high-purity argon at730°C.The influence of brazing time and gap size of joints was studied.The results revealed the maximum shear strength of(156±7)MPa for samples with150μm gap size at a holding time15min.The characterization and microstructure of the brazed joints were characterized by SEM,EDS and XRD.The results showed that increasing the time from5to15min could provide a better chance for the liquid interlayer to flow towards the base metal.However,the formation of some metallic phases such as Mn3W3C at brazing time longer than15min resulted in decreased shear strength of the joint.展开更多
In order to investigate the microstructure evolution and gain complete isothermal solidification time, transient liquid phase （TLP） bonding of IN-738LC superalloy was carried out using powdered AMS 4777 as the fille...In order to investigate the microstructure evolution and gain complete isothermal solidification time, transient liquid phase （TLP） bonding of IN-738LC superalloy was carried out using powdered AMS 4777 as the filler metal. The influence of gap size and bonding time on the joints was investigated. For example, complete isothermal solidification time for 40μm gap size was obtained as 45 min. In the case of lack of completion of isothermal solidification step, the remained molten interlayer cooled in the bonding zone under non-equilibrium condition andγ–γ′ eutectic phase formed in that area. The relationship between gap size and holding time was not linear. With the increase in gap size, eutectic phase width became thicker. In the diffusion affected zone, a much larger amount of alloying elements were observed reaching a peak. These peaks might be due to the formation of boride or silicide intermetallic. With the increase in gap size, the time required for bonding will increase, so the alloying elements have more time for diffusion and distribution in farther areas. As a result, concentrations of alloying elements decreased slightly with the increase in the gap size. The present bi-phasic model did not properly predict the complete isothermal solidification time for IN-738LC-AMS 4777-IN-738LC TLP bonding system.展开更多
Influences of gap size and cyclic-thermal-shock treatment on the mechanical properties of transient liquid phase（TLP） bonded IN-738 LC superalloy were investigated. For this purpose, TLP bonding of IN-738 LC superal...Influences of gap size and cyclic-thermal-shock treatment on the mechanical properties of transient liquid phase（TLP） bonded IN-738 LC superalloy were investigated. For this purpose, TLP bonding of IN-738 LC superalloy was carried out in a vacuum furnace using powdered AMS 4777 as the filler metal. The results showed that isothermal solidified zone（ISZ） consisted of Ni solid-solution and the distribution of alloying elements was homogeneous. High hardness of HV 409 and high shear strength of 506 MPa were observed in 40 μm gap sample. Alloying elements formed γ′ precipitates and the solid-solution in the ISZ. Hardness and shear strength of bonds were reduced with increasing the gap size（in range of 40-120 μm）. The fractured surfaces of complete isothermal solidified bonds showed dimpled rupture, but athermal solidified bonds showed cleavage fracture surface. 10, 20, 30 and 40 thermal-shock cycles were applied to 80 μm gap samples, respectively. The shear strength of the bond was measured to be 268 MPa after the 40 th thermal-shock cycle. The sample with gap size of 80 μm was failed due to crack nucleation on faying surface at 45 th thermal-shock cycle. The amount of the produced brittleness due to quenching the samples in water bath was attributed to the number of thermal-shock cycles.展开更多
Binary alloys have garnered significant attention for the development of the sodium-ion battery due to their ability to combine the advantages of single-phase alloys.However,these materials often demonstrate limited e...Binary alloys have garnered significant attention for the development of the sodium-ion battery due to their ability to combine the advantages of single-phase alloys.However,these materials often demonstrate limited electrochemical performance,and the relationship between their crystallization states and their sodium storage properties remains poorly understood.Here,we synthesize Bi-Sn binary alloys with various compositions via phase-separation metallurgy to explore the sodium storage properties of different crystalline structures.The results indicate that hypo-and hyper-eutectic Bi-Sn alloys readily form a“dendritic”primary phase at the non-eutectic interface,which aggravates structural degradation and increases internal resistance.In contrast,Bi-Sn alloys with optimized eutectic interfaces effectively control dendritic growth and reduce defects,resulting in enhanced microstructural stability and superior electrochemical performance.As results,the eutectic p-Bi_(57)Sn_(43)@C anode achieves a record-high specific capacity of 470.3 mAh g^(-1) at 1 C and exhibits remarkable long-term cycling stability,retaining 95.2%of its capacity after 1000 cycles at 20 C.The defect-free eutectic concept presented here establishes a valuable foundation for future studies of binary and polycrystalline eutectic alloys in electrochemical applications.展开更多
文摘WC-Co hard metal was furnace brazed by Ag-Cu-Zn+Ni/Mn filler alloy using a tube furnace under high-purity argon at730°C.The influence of brazing time and gap size of joints was studied.The results revealed the maximum shear strength of(156±7)MPa for samples with150μm gap size at a holding time15min.The characterization and microstructure of the brazed joints were characterized by SEM,EDS and XRD.The results showed that increasing the time from5to15min could provide a better chance for the liquid interlayer to flow towards the base metal.However,the formation of some metallic phases such as Mn3W3C at brazing time longer than15min resulted in decreased shear strength of the joint.
文摘In order to investigate the microstructure evolution and gain complete isothermal solidification time, transient liquid phase （TLP） bonding of IN-738LC superalloy was carried out using powdered AMS 4777 as the filler metal. The influence of gap size and bonding time on the joints was investigated. For example, complete isothermal solidification time for 40μm gap size was obtained as 45 min. In the case of lack of completion of isothermal solidification step, the remained molten interlayer cooled in the bonding zone under non-equilibrium condition andγ–γ′ eutectic phase formed in that area. The relationship between gap size and holding time was not linear. With the increase in gap size, eutectic phase width became thicker. In the diffusion affected zone, a much larger amount of alloying elements were observed reaching a peak. These peaks might be due to the formation of boride or silicide intermetallic. With the increase in gap size, the time required for bonding will increase, so the alloying elements have more time for diffusion and distribution in farther areas. As a result, concentrations of alloying elements decreased slightly with the increase in the gap size. The present bi-phasic model did not properly predict the complete isothermal solidification time for IN-738LC-AMS 4777-IN-738LC TLP bonding system.
文摘Influences of gap size and cyclic-thermal-shock treatment on the mechanical properties of transient liquid phase（TLP） bonded IN-738 LC superalloy were investigated. For this purpose, TLP bonding of IN-738 LC superalloy was carried out in a vacuum furnace using powdered AMS 4777 as the filler metal. The results showed that isothermal solidified zone（ISZ） consisted of Ni solid-solution and the distribution of alloying elements was homogeneous. High hardness of HV 409 and high shear strength of 506 MPa were observed in 40 μm gap sample. Alloying elements formed γ′ precipitates and the solid-solution in the ISZ. Hardness and shear strength of bonds were reduced with increasing the gap size（in range of 40-120 μm）. The fractured surfaces of complete isothermal solidified bonds showed dimpled rupture, but athermal solidified bonds showed cleavage fracture surface. 10, 20, 30 and 40 thermal-shock cycles were applied to 80 μm gap samples, respectively. The shear strength of the bond was measured to be 268 MPa after the 40 th thermal-shock cycle. The sample with gap size of 80 μm was failed due to crack nucleation on faying surface at 45 th thermal-shock cycle. The amount of the produced brittleness due to quenching the samples in water bath was attributed to the number of thermal-shock cycles.
基金supported by the National Natural Science Foundation of China(22309056,52002297 and U2004210)Knowledge Innovation Project of Wuhan City(2022010801010303)+3 种基金National Key R&D Program of China(2022YF2404800)Key R&D Projects of Hubei Province(2022BCA061)Application Foundation Frontier Project of Wuhan Science and Technology Program(2020010601012199)Basic Research Program of Shenzhen Municipal Science and Technology Innovation Committee(JCYJ20210324141613032)。
文摘Binary alloys have garnered significant attention for the development of the sodium-ion battery due to their ability to combine the advantages of single-phase alloys.However,these materials often demonstrate limited electrochemical performance,and the relationship between their crystallization states and their sodium storage properties remains poorly understood.Here,we synthesize Bi-Sn binary alloys with various compositions via phase-separation metallurgy to explore the sodium storage properties of different crystalline structures.The results indicate that hypo-and hyper-eutectic Bi-Sn alloys readily form a“dendritic”primary phase at the non-eutectic interface,which aggravates structural degradation and increases internal resistance.In contrast,Bi-Sn alloys with optimized eutectic interfaces effectively control dendritic growth and reduce defects,resulting in enhanced microstructural stability and superior electrochemical performance.As results,the eutectic p-Bi_(57)Sn_(43)@C anode achieves a record-high specific capacity of 470.3 mAh g^(-1) at 1 C and exhibits remarkable long-term cycling stability,retaining 95.2%of its capacity after 1000 cycles at 20 C.The defect-free eutectic concept presented here establishes a valuable foundation for future studies of binary and polycrystalline eutectic alloys in electrochemical applications.
