X-RAY TUBE CATHODE ASSEMBLY AND INTERFACE REACTION JOINING PROCESS

An x-ray tube cathode assembly ( 28 ) includes a support arm ( 36 ) comprising a first metal. A ceramic insulator ( 70, 82 ) has a first metalized surface ( 72, 86 ) wherein the metalized surfaces comprise a desired amount of the first metal. A first member of filler material ( 90 ) is in contact with the support arm ( 36 ) and the first metalized surface ( 72, 86 ) of the ceramic insulator ( 70, 82 ), the first member of filler material comprising at least a second metal ( 96 a, 96 b) wherein a first alloy system (FIG. 5 ) comprising the first and second metals includes an alloy minimum point percentage composition (P) of the first and second metals having a first alloy system minimum melting point (M) for the alloy minimum point percentage composition that is lower than both of the melting point of the first metal and second metal. A bonding region resulting from heating the cathode assembly causing diffusion bonding to proceed, the bonding region has a layer of alloy comprising the minimum point percentage composition (P) and the heating of the cathode assembly continues to a bonding temperature of at least the first alloy system minimum melting point (M) and holding at that temperature for a desired period of time.