Jones, Engineering Materials I, 3rd Ed, Butterworth-Heinemann, 2005, p. 279). (Source: M.F. Box 586, 34100 Trieste, Italy 3Center for Materials Science and … Ashby, D.R.H. For example, dislocation climb, concentration of vacancies, new slip systems, and grain boundary sliding all are diffusion-controlled and will affect the behaviour of materials at high temperatures. 2. It is also often claimed that the value of a stress exponent, n, obtained via creep rate measurements over a range of applied stress, is indicative of the dominant mechanism, with a low value (~1-2) indicating pure diffusional creep and a higher value (~3-6) suggestive of dislocation creep. Dislocation Jamming and Andrade Creep M.-Carmen Miguel,1 AlessandroVespignani,2 Michael Zaiser,3 and Stefano Zapperi4 1Departament de Fı´sica Fonamental, Facultat de Fı´sica, Universitat de Barcelona, Avinguda Diagonal 647, E-08028 Barcelona, Spain 2The Abdus Salam International Centre for Theoretical Physics, P.O. We report two-dimensional discrete dislocation dynamics simulations of combined dislocation glide and climb leading to "power-law" creep in a model aluminum crystal. Two flow laws were determined, one for samples containing minor amounts of melt (1-2%) and one for melt-free samples. The constitutive law for dislocation glide is typically exponential creep.. Dislocation glide leads to huge densities of dislocations within crystals. Dislocation creep is char-acterized by a power-law dependence of creep rate on stress and an exponential depen-dence of creep … laboratory, “power-law creep” (or dislocation creep) occurs via either the glide of dislo-cations or via the combined glide and climb of dislocations. This sort of creep is called dislocation (or power-law) creep. The approach fully accounts for matter transport due to vacancy diffusion and its coupling with dislocation motion. Creep tests were performed to complement the constant strain rate tests and to allow direct determination of the apparent activation energy. of Materials Science & Engineering, 2220 Campus Drive, Evanston, IL 60208, USA Eventually leads to strain hardening because the dislocations get tangled - they need good, intact crystal to migrate, and so are held up by other dislocations. Thus, although the Glen law provides an approximate description of ice flow in glaciers and ice sheets, its functional form is not explained by a single deformation mechanism. At lower stresses, a new régime is entered where n 1 power-law creep Slope n 3 to 8 low tail, n 1 The existence of q … Full length article Dislocation-based modeling of long-term creep behaviors of Grade 91 steels Jifeng Zhao a, *, Jiadong Gong a, Abhinav Saboo a, David C. Dunand b, Gregory B. Olson a, b a QuesTek Innovations LLC, 1820 Ridge Avenue, Evanston, IL 60201, USA b Northwestern University, Dept. Sample Preparation and Experimental Procedure 2.1. Creep Mechanisms The creep exponent n usually lies between 3 and 8. After presenting a description of experimental procedures and results, we discuss steps toward a generalized dislocation creep law for calcite. We have limited the experimental conditions to those required for dislocation creep, and have used only steady-state flow stresses measured during climb-accommodated dislocation creep to calculate the flow law parameters. Experimental studies find that neither dislocation creep (n ~ 4) nor grain boundary sliding (n ~ 1.8) have stress exponents that match the value of n ~ 3 in the Glen law. In addition, corrosion or ... n>1 (power law creep) between dislocation and diffusion creep, Philosophical Magazine A, 41:6, 871-882, DOI: 10.1080/01418618008243893 To link to this article: https://doi.or g/10.1080/01418618008243893