The high-temperature creep properties of materials processed using severe plastic deformation

Abstract

Abstract Processing through the application of severe plastic deformation (SPD) is now an accepted procedure for introducing very significant grain refinement into bulk solids. Typically, experiments show that the materials processed in this way have grain sizes in the submicrometer or even the nanometer range. This exceptional grain refinement provides an opportunity for conducting creep tests at elevated temperatures and examining the occurrence of creep flow through mechanisms where the creep rate varies inversely with the grain size. The present paper describes creep experiments conducted on two different representative materials subjected to SPD processing: high-purity aluminum and an aluminum 7034 alloy. The results demonstrate that the creep behavior depends critically upon the thermal stability of the ultrafine-grain microstructures.