AN IMPROVED METHOD OF INTRODUCING ADDITIONAL ALLOYING ELEMENTS INTO NB3SN IN INTERNAL-TIN PROCESSES

RECENTLY, THE SUCCESSFUL DEVELOPMENT OF A (NBTA)3SN (NIOBIUM-TANTALUM-TIN) MATERIAL HAS BEEN CONFIRMED BY DEMONSTRATING ITS USE IN A 20.4 T MODEL MAGNET FOR A 900 MHZ SPECTROMETER. THE MATERIAL WAS PRODUCED IN LONG PIECELENGTHS. A SIMILAR CONDUCTOR DESIGN THAT USED (NBTI)3SN (NIOBIUM-TITANIUM-TIN) WAS DEVELOPED FOR THE LAWRENCE LIVERMORE LABORATORY FOR USE IN THEIR POP COIL PROGRAM. THIS CONDUCTOR, WHICH WAS PRODUCED IN LARGE QUANTITIES, SUFFERED FROM POOR AND VARIABLE PIECELENGTHS. ALTHOUGH THE EXACT REASON FOR THIS DIFFERENCE IN BEHAVIOR ISNOT KNOXWN FOR CERTAIN, IT MIGHT BE RELATED TO THE APPARENT HIGH WORK-HARDENING CHARACTERISTIC OF THE TI-CONTAINING ALLOY COMPARED WITH THAT OF THE TA ALLOY. TI IS CHEAPER THAN TA, AND LESS IS REQUIRED TO GIVE SUPERIOR PROPERTIES IN THE INTERMEDIATE FIELD REGION REQUIRED BY THE INTERNATIONAL THERMONUCLEAR EXPERIMENTAL REACTOR (ITER) AND SIMILIAR FUSION DEVICES. CONSIDERABLE INCENTIVE EXISTS TO OVERCOME THIS PIECELENGTH PROBLEM. BECAUSE MINIMAL PROBLEMSOF THIS NATURE HAVE BEEN EXPERIENCED IN THE PAST WHEN USING PURE NB RODS IN A COPPER (CU) MATRIX, THESE RODS ARE EMPLOYED IN THIS WORK. TH TI, NECESSARY FOR THE HIGH FIELD PROPERTIES, IS INTRODUCED BY INCORPORATING IT INTO THE MATRIX AS A CUTI ALLOY, AS IN THE BRONZE PROCESS. PHASE I IS CONCERNED WITH COMPARING THE PROPERTIES OBTAINED FROM A TIRAL BILLET WITH NB RODS AND A CUTI ALLOY MATRIX WITH A SIMILIAR DESIGN OF CONTROL BILLET WITH NB-ONE WT% TI RODS AND A CU MATRIX. IN THE PAST, PROBLEMS HAVE BEEN ENCOUNTERED WHEN ATTEMPTS WERE MADE TO COLD BOND HARD SUBELEMENTS IN THE TIN-CORE PROCESS. THE RECENTLY DEVELOPEDTUBULAR-TIN-SOURCE (TTS PROCESS HAS PROVED TO BE FAR LESS SENSITIVE TO THE HARDNESS OF THE MATRIX BECAUSE A HOT ISOSTATIC PROCESSING STEP IS USED, AND NO COLD RESTACKING OFSUBELEMENTS IS INVOLVED. THIS WAS PROVED RECENTLY WITH MATERIAL MADE WITH DISPERSION-HARDENED CU SURROUNDING THE FILAMENTS. FOR THIS REASON, THE TTS PROCESS IS BEING USED FOR BOTH BILLETS MADE IN THIS WORK.