Heat treatments, microstructure and properties of internal-tin Nb/sub 3/Sn

The decrease of temperature ramp rate during heat treatments of the internal tin process causes an increase of the critical current density at low and medium magnetic fields (4-16T). This paper investigates the metallurgical origin of this benefit by considering the effects of a change of heating rate on the phase transformations of bronze and on the filament recrystallization. The low temperature formation of Nb/sub 3/Sn is important for the critical current density of this material. This is explained by the composite microstructure evolution.