The internal microstructure of new high modulus, pitch-based, post-cre
ep carbon filaments is compared to that as-received and is similarly c
ompared to post-creep and as-received PAN-based filaments. The structu
re of the carbon filaments is studied using several techniques: electr
on diffraction, scanning electron microscopy, transmission electron mi
croscopy, and X-fay diffraction.