Page 206 - Fiber Fracture

STRENGTH AND FRACTURE OF METALLIC FILAMENTS 191

Fig. 5. Microstructure of a 25 km diameter Au wire in 4 annealing states: as-drawn, 15 min 150"C, 15 min
320°C. and 10 rnin 700°C.
1

i
b

Fig. 6. Longitudinal microstructure of an as-drawn Cu wire (38 km diameter). TEM observations reveal the
heavily deformed and elongated 'grains' of 0.01-0.3 krn thickness that are completely aligned along the
drawing direction. (From Busch-Lauper, 1988.)

that a certain crystallographic direction aligns along the radial direction. This, together
with the fiber orientation, fixes of course also the tangential orientation. Since the
evolution of the texture is driven by the plastic deformation during the drawing process
the final textures are not always equally well developed throughout the wire. The radial
symmetry sometimes develops only near the surface.
The drawing of bcc metals generally results in a [110] fiber texture, whereas fcc
metals develop [loo] and [lll] textures (Grewen, 1970). The degree of the orientational