Electron Backscatter Diffraction Analysis on ${\hbox {Nb}}_{3}{\hbox {Sn}}$ and ${\hbox {Nb}}_{3}{\hbox {Al}}$ Multifilaments

Observations of fractured cross sections, which are frequently used to determine the grain size distribution in Nb
₃
Sn, cannot be performed for Nb
₃
Al since transgranular fracture is the dominant fracture mode. Instead, we have evaluated the grain size of Nb
₃
Al using electron backscatter diffraction (EBSD). To check the validity of EBSD analysis for A15 grain structures, bronze-route Nb
₃
Sn filaments were also examined by EBSD. The deformation-and-transformation of bcc supersaturated-solid solution Nb(Al)
_ss
was found not only to homogenize and refine the grain size of the resultant Nb
₃
Al but also to increase a ratio of high angle grain boundaries to low angle grain boundaries. The texture studies were made by pole figure works: the Nb(Al)
_ss
retains a 〈110〉 fibrous texture as well as the filament barrier (Nb, Ta) does. The transformed Nb
₃
Al also has the weak 〈110〉 fibrous texture, whereas Nb
₃
Sn has almost never texture. A clear relationship between
Jc
and the inverse of grain size was not observed.