Effect of cross slips on multiple slips and recrystallization in < 111 > and < 001 > Al single crystals

99.99 mass% < 111 > and < 001 > aluminum single crystal specimens were defo rmed in tension to strains of about 20%. Multiple slipped structures withou t deformation bands were observed. In the < 111 > aluminum single crystal d eformed at room temperature, short and wavy slip traces are observed becaus e of the difficulty of cross slips which comes from the orientation-depende nce. The microstructure shows layered cell structures composed of dense dis location walls. In < 001 > aluminum single crystal deformed at liquid nitro gen temperature 77 K, short and wavy slip traces similar to those in the ab ove < 111 > ones are also observed because of the difficulty of cross slips which comes from the temperature-dependence. The microstructure presents s mall cell structures with high dislocation density even in the cells as wel l as along the cell walls. In the above two kinds of deformed aluminum sing le crystals, the formation of recrystallized grains is very easy. On the ot her hand, in the < 001 > aluminum single crystal deformed at room temperatu re, many cross slips with long-distance steps are observed because each of eight primary slip systems has the corresponding cross (another primary) sl ip system. The microstructure gives polygonal cells with loose dislocations . After annealing no recrystallized grain forms. The stress values at 20% s trains of the stress-strain curves in the < 001 > (room temperature), < 111 > (room temperature) and < 001 > (77 K) aluminum single crystals are 22, 7 1 and 106 MPa, respectively.