ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

On Creep Behaviour of Several Metallic Materials at Low Stresses and Elevated Temperatures

L. Kloc and J. Fiala

Institute of Physics of Materials, Academy of Sciences of the Czech Republic, CZ-616 62 Brno

Abstract: Viscous creep was observed in many materials at temperatures close to the value of one half of absolute melting temperature at very low creep rates. The results were interpreted as diffusional creep and/or Harper-Dorn creep. Not all of creep mechanisms acting at conditions mentioned above can explain their own primary stage. Nevertheless, the primary creep has been observed in almost all creep experiments. Hence, special primary creep mechanisms must be responsible for primary creep observed.Many creep results are in very good agreement with the Coble theory, and can support the idea of the diffusional creep operating as an important deformation mechanism under certain conditions. Unfortunately, the theory of diffusional creep seems to be too simplified to describe accurately the diffusional creep processes. In several materials, dependence of the creep rate on grain size corresponds to the Coble mechanism for grain sizes below approximately 100 μm, while large data scattering for coarse grain sizes replaces this dependence. This behaviour used to be interpreted as a transition from the diffusional to the Harper-Dorn creep regime. The structural parameter responsible for large scattering of creep rates at large grain sizes has not been identified yet. This paper discusses the transition from viscous to power-law creep regime for two materials with very different structure.

Full paper in Portable Document Format: 533a155.pdf

Chemical Papers 53 (3) 155–164 (1999)