Abstract
⟨111⟩ and ⟨001⟩ aluminum single crystal specimens with 99.99 mass% purity were 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 recognized because of the difficulty of cross slips. The difficulty is due to the 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 specimens are also observed because of the difficulty of cross slips. This difficulty is due to the temperature dependence of cross slips. The dislocation structure is composed of small isotropic cells with high dislocation density 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 an appropriate cross (i.e. another primary) slip system geometrically. The dislocation structure gives polygonal cells with low dislocation density. After 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.
