Quergleitspannung und stapelfehlerenergie von kupferreichen mischkristallen

Abstract

Tensile tests were performed on single crystals of binary and ternary copper alloys with uniform initial orientation and with admixtures of gallium or germanium and electron concentrations of 1.00 ≦ e/ a ≦ 1.15. In particular, the dependence of the critical stress for cross slip τ III on the true strain rate ȧ (at 293°K) and on temperature were measured. Using the relation calculated by Seeger and coworkers for the dependence of the quantity S = ∂ In τ III/ ∂ ln a ̇ on the stacking fault energy γ, a value γ = 50 ± 6 erg/cm 2 is obtained for copper. Th quantity S and the absolute value of τ III are determined by e/ a only. S( e/ a) reaches a maximum for e/ a ≈ 1.04 and decreases then rapidly with e/ a. Stacking fault energies of 87 ± 13 and 80 ± 7 erg/cm 2 are obtained for e/ a = 1.03 and 1.06, respectively. S( γ) is known, however, only for γ-values which are not too small, and cannot be employed for the evaluation of τ III for e/a ≧ 1.1. In the latter case, stacking fault energies as measured (on dislocation nodes) by Howie and Swann using electron microscope techniques permit an experimental determination of the function S( γ) in connection with S from τ III( a ̇ ) . As was expected, S( γ) ≈ 0 if γ ≈ 0. The work hardening parameters of stages I and II are reported.