Cyclic plasticity of nickel single crystals at elevated temperatures
1997; Elsevier BV; Volume: 45; Issue: 9 Linguagem: Inglês
10.1016/s1359-6454(97)00030-x
ISSN1873-2453
AutoresJörg Bretschneider, C. Holste, B. Tippelt,
Tópico(s)High Temperature Alloys and Creep
ResumoSingle slip oriented nickel crystals have been cyclically deformed at deformation temperatures between 293 K and 900 K until saturation of the stress amplitude. Persistent slip bands (PSBs) with a typical ladder-like dislocation substructure occur at temperatures up to 800 K. At 600 K and 750 K the measured cyclic stress-strain curves (CSSCs) exhibit extended ranges in which the saturation stress amplitude is nearly independent of the applied plastic strain amplitude. The plastic strain amplitdes at the upper and the lower borders of these "plateaus" in the CSSCs decrease with increasing temperature. Most of the measured structure lengths of the wall/channel arrangement in the PSB ladders and of the dipole arrangement in the PSB walls have been found to become larger at elevated temperatures. The only exception observed is the wall thickness which remains constant, independent of the temperature. Analysis of the measured data on the basis of current modelling approaches shows that the local flow stresses and the residual stresses are reduced at elevated temperatures.
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