多孔鎢與鉬高溫硬銲之研究

Abstract

研究主要係針對多孔鎢基材對多孔鎢基材、鉬基材對鉬基材及多孔鎢基材對鉬基材進行高溫硬銲製程研究，研究中共選用40Ti-35Ni-25Nb (wt%)、50Ti-35Ni-15Nb (wt%)、60Ti-25Ni-15Nb (wt%)、純Pd 、純Ti、Ti-15-3及60Mo-40Ru (wt%)等7種不同的高溫硬銲銲片進行硬銲製程評估，硬銲製程中藉由改變硬銲溫度 、硬銲時間及銲片厚度，用以評估硬銲製程參數與顯微結構之關係。實驗結果顯示40Ti-35Ni-25Nb (wt%)、50Ti-35Ni-15Nb (wt%)及60Ti-25Ni-15Nb (wt%)等3種填料之硬銲溫度係低於1350°C。對於porous W/40Ti-35Ni-25Nb/Mo硬銲件而言，其銲道主要由具延性之相所組成，且40Ti-35Ni-25Nb填料對於多孔鎢基材之熔滲相對於50Ti-35Ni-15Nb填料及60Ti-25Ni-15Nb填料具最小之熔滲深度，因此，40Ti-35Ni-25Nb填料係有可能被用於多孔鎢基材與鉬基材之異材接合。對於Mo/40Ti-35Ni-25Nb/Mo、Mo/50Ti-35Ni-15Nb/Mo及 Mo/60Ti-25Ni-15Nb/Mo等3種硬銲件硬銲後，其銲道具有相似之顯微結構變化，其中Mo/60Ti-25Ni-15Nb/Mo 硬銲件於1250°C/600s硬銲時可獲得最高之彎曲強度(526 MPa)。對於Pd填料而言，研究中成功以Pd銲片完成多孔鎢基材對多孔鎢基材、鉬基材對鉬基材及多孔鎢基材對鉬基材之硬銲接合，接合後之銲道顯微組織無可見之缺陷或介金屬相產生，此外，以1610°C/600s進行硬銲接合時，熔融之Pd填料對於多孔鎢基材之熔滲深度極為輕微(<30 μm)，因此，Pd填料相當有潛力被應用在多孔鎢基材與鉬基材之接合。由於銲道出現嚴重之孔洞問題，研究中並無法成功以純Ti或Ti-15-3填料硬銲接合多孔鎢基材與鉬基材。對於Mo/60Mo-40Ru/Mo硬銲件而言，研究中分別以1970°C/600s 及2000°C/600s進行硬銲接合皆可獲得品質良好之接點，其銲道主要係由σ 相和Mo-rich相所組成，而對於porous W/60Mo-40Ru/Mo硬銲件來說，其銲道顯微組織與Mo/60Mo-40Ru/Mo硬銲件相似，但品質良好之接點僅能由硬銲條件2000°C/600s獲得，較低之硬銲溫度並無法獲得良好之硬銲接點，由於60Mo-40Ru填料係可成功進行鉬基材對鉬基材及多孔鎢基材對鉬基材之硬銲接合，因此，60Mo-40Ru填料係可被應用在高溫領域中多孔鎢基材與鉬基材之硬銲接合。

The study of high temperature brazing porous W/porous W, Mo/Mo and porous W/Mo has been performed in the experiment. Seven brazing filler foils are used in the experiment, including: 40Ti-35Ni-25Nb in wt%, 50Ti-35Ni-15Nb in wt%, 60Ti-25Ni-15Nb in wt%, pure Pd, pure Ti, Ti-15-3, 60Mo-40Ru in wt%. Microstructural evolution of the joint using various brazing conditions, including brazing temperature, time and thickness of the filler foil has been evaluate in the experiment. The 40Ti-35Ni-25Nb, 50Ti-35Ni-15Nb and 60Ti-25Ni-15Nb filler foils are featured with low brazing temperature of below 1350°C. For the porous W/40Ti-35Ni-25Nb/Mo joint, the brazed joint contains ductile phases and shows least penetration of molten braze into the porous W substrate. The 40Ti-35Ni-25Nb filler foil shows potential in dissimilar brazing porous W and Mo. Similar microstructural evolution is observed for Mo/40Ti-35Ni-25Nb/Mo, Mo/50Ti-35Ni-15Nb/Mo and Mo/60Ti-25Ni-15Nb/Mo joints. The Mo/60Ti-25Ni-15Nb/Mo joint brazed at 1250°C for 600s demonstates the highest bending strength of 526 MPa. For brazing porous W/porous W, Mo/Mo and porous W/Mo joints, successful brazed joints are obtained from using the Pd filler foil. Brazed joints are fully dense and free of any intermetallic phase. Meanwhile, infiltration of the Pd-rich melt into the porous W substrate is trivial, limited below 30 μm for the specimen brazed at 1610°C for 600s. The application of Pd filler metal shows great potential in brazing porous W and Mo. The application of Ti and T15-3 foil in brazing porous W/Mo are not appropriate due to the presence of voids in the brazed joint. For Mo/60Mo-40Ru/Mo joint, sound joint is obtained from brazing at 1970°C and 2000°C for 600s, respectively. The brazed joints are comprised of σ and Mo-rich phases. For Mo/60Mo-40Ru/porous W joint, sound bonding is achieved only from brazing at 2000°C for 600s, and similar microstructure of the joint is obtained. The 60Mo-40Ru braze alloy shows potential in bonding Mo/Mo and porous W/Mo for high temperature applications.