Deformation and failure modes of CVD textured tungsten in [001], [011]
and random orientations subjected to various loading rates under unia
xial compression are characterized using optical and electron microsco
py. It is found that [001] orientation undergoes large homogeneous def
ormation in the range of strain rates investigated (10(-2)-10(4)/s). E
volution of dislocation substructure in [001] tungsten is characterize
d by TEM studies. Under quasi-static loading rates, elongated dislocat
ion cell formation is observed. At high strain rates, the dislocation
density initially increases with respect to strain and then saturates
when the temperature rise due to adiabatic heating becomes significant
. At true strains beyond 2 the dislocations form well defined cells, w
ith the cell walls containing very high dislocation densities. The def
ormation in [011] orientation is relatively less homogeneous under qua
si-static loading, but under high strain rate loading the deformation
is characterized by slip lines, extensive twinning and grain boundary
cracking. Fine grain polycrystalline specimens fail in a typical britt
le manner.