Manufacture Technology And Properties Characterization Of Bonding Between W-Cu And Cu

Abstract:The high mismatch on coefficient of thermal expansion between W and Cu makes the bonding between W and Cu on divertor application become a problem. In this paper, the author in view of the bonding technology between W-Cu and Cu, carried out a series of W-Cu and Cu bonding technology research by using improved diffusion bonding technology. First, W-Cu and Cu implements the metallurgical combination of at a high temperature by liquid diffusion bonding. Then diffusion bonding was studied by adding an interlayer powder based on previous work. Finally, under the same bonding technology, diffusion bonding was studied with a high-energy activation interlayer powder. The main conclusions showed that:(1)The results of liquid phase diffusion bonding process found that, the interface between W-25Cu and Cu is intact without pore, but no W element diffusion. W-25Cu/Cu bonding sample tensile strength is163.13MPa. The fracture mode of Cu phase’s tear shows the typical ductile fracture.(2) The Fe-Cu composite powder was prepared by mechanical alloying, and used as the interlayer of diffusion bonding between W-25Cu and Cu. Compare to liquid phase diffusion bonding, the bonding temperature was decreased and the process is more stable.(3) The tensile strength of bonded sample under1050℃for2h was decreased by the rise of Cu content. Micro structure and micro hardness testing show that the interface between the interlayer and the Cu was good, complete and flawless; The interface between W-25Cu and Cu deteriorates as the Cu contents rise. Microhardness changes show gradient along the direction perpendicular to the interface.(4) The tensile strength of bonded sample under1050℃for4h was also decreased by the rise of Cu contents. When Fe-50Cu composite powder was served as an interlayer, diffusion of Fe in W is more sufficient, but the microhardness of W-25Cu edge and interlayer was high with the extension of time of heat preservation and the bonding strength decreaseed, which suggests that might generate a hard brittle phase of Fe-W intermetallic compound.(5) the interlayer powder was activated significantly, and compared with the bonded sample without activated powder, the interface roughness, density are improved. The diffusion of Fe element in W-25Cu was also deepened. Tensile strength decreases with the rise of Cu content in the interlayer powder.