IMPROVEMENT OF THE PROPERTIES OF TERNARY NIOBIUM-TITANIUM- TANTALUM ALLOYS

THIS WORK IS DESIGNED TO CARRY OUT A COMPREHENSIVE INVESTIGATION OF MULTIFILAMENTARY MATERIALS CONTAINING NIOBIUM-TITANIUM-TANTALUM (NBTITA) ALLOYS TO DETERMINE THE ADVANTAGES THAT THESE MATERIALS OFFER OVER THOSE CONTAINING NBTI BINARY ALLOYS IN 1.8 K AND 4.2 K OPERATION. THE PHASE I WORK CONCENTRATES ON THE NB-44 WT.% TA ALLOY BECAUSE OF ITS AVAILABILITY; THE ALLOY'S PROPERTIES ARE BEING COMPARED IN THREE DIFFERENT STATES OF HEAT TREATMENT AND COLD WORK WITH THOSE OF THE NB-44 WT.% TI-15 WT.% TA PREVIOUSLY INVESTIGATED. THE RELATIVE WORK-HARDENING CHARACTERISTICS OF THESE VARIOUS ALLOYS ARE BEING DETERMINED. THE RESULTS MAY GIVE AN INDICATION OF THE PIECELENGTH CHARACTERISTICS THAT WILL ULTIMATELY BE OBSERVED. THE CRITICAL FIELD OF THE MATERIAL IN THE VARIOUS CONDITIONS OF COLD WORK AND HEATTREATMENT BEFORE SECOND EXTRUSION WILL BE MEASURED. THE RESPONSE OF THE FINISHED MULTIFILAMENTARY WIRE TO VARIOUS HEAT TREATMENT TIMES AND TEMPERATURES WILL BE USED TO DETERMINE THE RATE AND EXTENT OF THE PRECIPITATION OF -TI IN THE TERNARY COMPARED WITH THAT IN THE BINARY. IN PHASE II, A BROADER INVESTIGATION OF THE PROPERTIES AND STRUCTURE (INCLUDING TRANSMISSION ELECTRON MICROSCOPE INVESTIGATIONS) WILL BE CARRIED OUT TO EXPLAIN THE RELATIONSHIP BETWEEN THEM. SCALE-UP WILL BE PERFORMED AND THE EFFECT OF THE ALLOY COMPOSITION ON PIECELENGTH WILL BE DETERMINED.