Metallurgical and shear strength of brazed bulk pure copper by microwave hybrid heating

Brazing of metallic material using microwave energy has been the recent research focus in the microwave-material processing area. A microwave susceptor material of graphite was placed together for hybrid heating to improve processing efficiencies. The function of the graphite susceptor was to initiate the coupling of microwave radiation to the heated material. In this study, bulk Copper (Cu) with Cu-7.0Ni-9.3Sn-6.3P amorphous filler metal (wt.%) were brazed using microwave hybrid heating. The effect of graphite susceptor mass (within 5 grams) on the brazed joints was characterized systematically. Results showed that the heating rate increased with the amount of the graphite susceptor. The intermetallics of Cu3P and (Cu, Ni)3P phase were observed in the brazed joint area. It was found that the use of graphite susceptor results in higher brazing temperature, which enhanced the atomic diffusion rate between the filler elements. The increase of susceptor mass during heating processes led to the decreasing values of the shear strength of the brazed joint. The highest shear strength was obtained for the brazing using 2 grams graphite powder at 5 minutes heating time.