The plastic deformation of polycrystalline 3N-purity material was studied in compression at 23 to 532C, using a strain rate of 8.3 x 10-4/s. The rate-controlling mechanism, at homologous temperatures of 0.28 to 0.65 (σ/μ > 3 x 10-4), was deduced to be the intersection of forest dislocations; involving an Helmholtz free energy of 113kJ/mol (0.16μb3). The forest dislocation obstacles became ineffective at an homologous temperature of about 0.65. The kinetics at an homologous temperature of 0.75 (σ/μ < 3 x 10-4), were in agreement with the Weertman-Dorn creep equation. At homologous temperatures below 0.5, a decrease in strain hardening with strain and temperature was attributed to cross-slip; leading to a brittle-ductile transition at an homologous temperature of 0.5. It was deduced that dislocation climb became more important at higher temperatures. The stress-strain curves could be described reasonably well by the Bergström-Roberts dislocation multiplication model.

The Rate-Controlling Mechanism(s) during Plastic Deformation of Polycrystalline NaCl at 0.28–0.75Tm. H.Conrad, D.Yang: Journal of Materials Science, 1999, 34[4], 821-6