Low-temperature creep behavior of ultrafine-grained 5083 Al alloy processed by equal-channel angular pressing

Abstract

Low temperature creep behavior of ECAPed Al 5083 alloy with grain sizes of approximately 300 nm was investigated at temperatures of 498, 523 and 548 K. The value of the stress exponent was found to be 3.5 at a low stress level and increased to 5.0 at a high stress level. At the low stress level, the creep curve exhibits typical class II behavior due to the accumulated strain during the ECAP process, even though the creep is controlled by solute-drag processes with a stress exponent of 3.5. The average value of Q obtained from the analysis of the data is close to that for dislocation pipe diffusion. Therefore, on the basis of the activation energy in a temperature range of 498K to 548K at low and high stress level, the creep deformation is controlled by dislocation glide and climb processes, respectively, and the rate-controlling diffusion step might be dislocation pipe diffusion.