STRESS DISTRIBUTION IN A SLIP TRACE OF DEFORMED Ni_3Ge SINGLE CRYSTALS

摘要

The shear-stress distribution produced by distortion of Ni_3Ge single crystals under compression is studied. The evolution of the dislocation structure during deformation of Ni_3Ge single crystals of various orientations at T = 77, 293, 523, 673, and 873 K is analyzed. It was found that, up to failure strains, the dislocation structure is characterized by a uniform dislocation distribution. Regardless of the strain-axis orientation, the linear relation T = f(ρ~(0.5)) is valid for all the test temperatures except for T = 77 K. The deviation from the linear relation at T = 77 K is due to the suppressed thermally activated slip of dislocations in nonuniform-strain fragments at the specimen edges. In these fragments, the shear stresses are substantially reduced, and hence, the stresses produced by the dislocation cluster retard the development of slip in this trace.