Fabrication Of The Copper-based Brazing Filler Materials For Brazing Tungsten/CuCrZr Alloy

Divertor is the significant composition of modern International Thermalnuclear Experimental Reactor(ITER). It consists of two major parts:plasma facing materials, which mainly refer to tungsten and heat sink materials, which often mean CuCrZr alloy. W/Cu joints have to face great differences in physical properties such as coefficient of thermal expansion, which would inevitably cause quality degradation of the joints. By far, brazing has been considered as the most promising method for jointing W/CuCrZr alloy. In this paper, new type of copper-based brazing fillers have been developed based on the unique advantages of brazing technique. The new optimized brazing parameters have also been determined by studying the microstructure, morphology and performances of W/CuCrZr alloy joints meanwhile. Detailed experimental results are as follows:1) New type of CuMnSiCr system brazing fillers have been developed with the composition Cu69Mn3oCro.sSio.5 represented, overcoming the disadvantage that high Mn content of the traditional CuMn brazing alloys. The new brazing alloy has been found with single FCC phase, with liquidus 915℃. Qualified W/CuCrZr alloy brazing joints can be obtained utilized by the the fillers at brazing temperature of 940℃. The compactness and elements diffusion of the joints have been verified by SEM and EDX and no obvious grain coarsening of the substrate was found. The results of the brazing joints mechanical analysis shows that the hardness of brazing seams is 132HV.2) New type of CuMnAl system brazing fillers have been developed with the composition Cu71.5Mn21Al7.5 represented, overcoming the disadvantage that high Mn content of the traditional CuMn brazing alloys. The new brazing alloy has been found with single FCC phase, with liquidus 924℃. Qualified W/CuCrZr alloy brazing joints can be obtained utilized by the the fillers at brazing temperature of 940℃. The compactness and elements diffusion of the joints have been verified by SEM and EDX. The results of the brazing joints mechanical analysis shows that the hardness of brazing seams is 134HV.3) New type of Cu-based amorphous brazing fillers have been developed with the compositions Cu47Ti33Zr11Ni8Si1. The new brazing alloy has been found with single amorphous phase, with liquidus 886℃. Qualified W/CuCrZr alloy brazing joints can be obtained utilized by the the fillers at brazing temperature of 900℃. The compactness and elements diffusion of the joints have been verified by SEM and EDX. The results of the metallographic analysis shows that the grain sizes of CuCrZr alloy substrates are small and homogeneous. The results of the brazing joints mechanical analysis shows that the hardness of brazing seams is 540HV.