The brazing of Al 2O 3 to Nb was achieved by the method of transient liquid phase (TLP) bonding. Ti foil and Ni 5V alloy foil were used as interlayers for the bonding. The base materials were brazed at 1 4231 573 K fo...The brazing of Al 2O 3 to Nb was achieved by the method of transient liquid phase (TLP) bonding. Ti foil and Ni 5V alloy foil were used as interlayers for the bonding. The base materials were brazed at 1 4231 573 K for 1120 min. The results show that the shear strength of the joint first increases and then decreases with increasing holding time and brazing temperature. The joint interface microstructure and elements distribution were investigated. It can be concluded that a composite structure, in which the base metals are solid solution Nb(V) and Nb(Ti) reinforced by Ni 2Ti, is formed when the brazing temperature is 1 473 K and holding time 15 min, and a satisfactory joint strength can be achieved. The interaction of Ti foil and Ni 5V foil leads to the formation of liquid eutectic phase with low melting point, at the same time the combination of Ti come from the interlayer with O atoms from Al 2O 3 results in the bonding of Al 2O 3 and Nb.展开更多
Microscopic phase field simulation is performed to study antisite defect type and temporal evolution characteristic of D022-Ni3V structure in Ni75AlxV25-x ternary system.The result demonstrates that two types of antis...Microscopic phase field simulation is performed to study antisite defect type and temporal evolution characteristic of D022-Ni3V structure in Ni75AlxV25-x ternary system.The result demonstrates that two types of antisite defect VNi and NiV coexist in D022 structure;however,the amount of NiV is far greater than VNi;when precipitates transform from D022 singe phase to two phases mixture of D022 and L12 with enhanced Al:V ratio,the amount of VNi has no evident response to the secondary L12 phase,while NiV exhibits a definitely contrary variation tendency:NiV rises without L12 structure precipitating from matrix but declines with it;temporal evolution characteristic and temperature dependent antisite defect VNi,NiV are also studied in this paper:The concentrations of the both defects decline from high antistructure state to equilibrium level with elapsed time but rise with elevated temperature;the ternary alloying element aluminium atom occupies both α and β sublattices of D022 structure with a strong site preference of substituting α site.展开更多
文摘The brazing of Al 2O 3 to Nb was achieved by the method of transient liquid phase (TLP) bonding. Ti foil and Ni 5V alloy foil were used as interlayers for the bonding. The base materials were brazed at 1 4231 573 K for 1120 min. The results show that the shear strength of the joint first increases and then decreases with increasing holding time and brazing temperature. The joint interface microstructure and elements distribution were investigated. It can be concluded that a composite structure, in which the base metals are solid solution Nb(V) and Nb(Ti) reinforced by Ni 2Ti, is formed when the brazing temperature is 1 473 K and holding time 15 min, and a satisfactory joint strength can be achieved. The interaction of Ti foil and Ni 5V foil leads to the formation of liquid eutectic phase with low melting point, at the same time the combination of Ti come from the interlayer with O atoms from Al 2O 3 results in the bonding of Al 2O 3 and Nb.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 50671084 and 50875217)the Doctorate Foundation of Northwestern Polytechnical University of China (Grant No. CX200806)+1 种基金the China Postdoctoral Science Founda-tion Funded Project (Grant No. 20070420218)the Natural Science Foundation of Shaanxi Province of China
文摘Microscopic phase field simulation is performed to study antisite defect type and temporal evolution characteristic of D022-Ni3V structure in Ni75AlxV25-x ternary system.The result demonstrates that two types of antisite defect VNi and NiV coexist in D022 structure;however,the amount of NiV is far greater than VNi;when precipitates transform from D022 singe phase to two phases mixture of D022 and L12 with enhanced Al:V ratio,the amount of VNi has no evident response to the secondary L12 phase,while NiV exhibits a definitely contrary variation tendency:NiV rises without L12 structure precipitating from matrix but declines with it;temporal evolution characteristic and temperature dependent antisite defect VNi,NiV are also studied in this paper:The concentrations of the both defects decline from high antistructure state to equilibrium level with elapsed time but rise with elevated temperature;the ternary alloying element aluminium atom occupies both α and β sublattices of D022 structure with a strong site preference of substituting α site.
