M. Tagami et al., Effect of cross slips on deformation microstructure and recrystallization in < 111 > and < 001 > Al single crystals, MATER TRANS, 42(9), 2001, pp. 2013-2020
(111) and (001) aluminum single crystal specimens with 99.99 mass% purity w
ere deformed in tension to strains of about 20%. In all specimens, multiple
slip structures without deformation bands were observed, In (111) specimen
deformed at room temperature of 293 K (RT), fine wavy slip traces are reco
gnized because of the difficulty of cross slips. The difficulty is due to t
he tensile-orientation dependence of cross slips. The dislocation structure
shows layered cell structures composed of cell walls with high dislocation
density. In (001) specimen deformed at liquid nitrogen temperature of 77 K
(LNT), complex fine slip traces similar to those in the case of (111) RT s
pecimens are also observed because of the difficulty of cross slips. This d
ifficulty is due to the temperature dependence of cross slips, The dislocat
ion structure is composed of small isotropic cells with high dislocation de
nsity around their cell walls. In the above two kinds of deformed aluminum
single crystals, the formation of recrystallized grains (RGs) is very easy.
On the other hand, in the (001) specimen deformed at RT, many cross slips
with large steps are seen because all the eight primary slip systems have a
n appropriate cross (i.e. another primary) slip system geometrically. The d
islocation structure gives polygonal cells with low dislocation density. Af
ter annealing no recrystallized grain is formed in the specimen. The stress
values of the stress-strain curves in the (001) (RT), (111) (RT) and (001)
(LNT) specimens are 22 MPa at 25% strain, 71 MPa at 22% and 106 MPa at 20%
, respectively.