Cathode filaments are recrystallized to a microstructure that maintains ductility for proper alignment and electron emission capability. The method comprises controlled heating of a cathode filament from an ambient temperature T.sub.amb to its recrystallization temperature T.sub.recryst ; controlled holding of the cathode filament at the temperature T.sub.recryst ; and controlled cooling of the cathode filament from the temperature T.sub.recryst to the ambient temperature T.sub.amb. The cathode filament is usable in an x-ray tube and can be formed of a tungsten-rhenium material.