Phase transformation during the final stage of Ag/2223 tape processing has
been investigated through quenching and normal cooling in a specially-desig
ned two-step sintering process. It was found that the phase assemblage in t
he final tape was determined by the equilibrium composition at the sinterin
g temperature and also from any phase transformation which occurred on cool
ing. A two-stage sintering procedure in the final thermal cycle was found t
o be effective in transforming the liquid (or amorphous phase) and residual
2201 into 2212 and 2223. However, the annealing temperature during the fin
al step was critical to the final phase assemblage. The optimal annealing t
emperature of the second step in the two-step process was around 825 degree
s C, where all the low T-c phases and impurities were at a minimum. Anneali
ng at temperatures below 810 degrees C, resulted in a substantial increase
in 3221, and a lower J(c). Annealing above 825 degrees C led to a large 221
2 fraction with a small amount of 2201 because of insufficient time needed
to convert these phases into 2223 on normal cooling.