Rate Independent and Rate Dependent Structural Evolution during Severe Plastic Deformation

High pressure torsion (HPT) deformation enables the grain refinement of bulk materials until a saturation region is reached where no further microstructural refinement can be observed, The influence of deformation temperature. alloying and strain rate on the saturation region was examined by using pure aluminum, an Al-l mass%Mg, alloy and an Al-3 mass%Mg alloy. The deformation temperature was varied between -196 degrees C and 450 degrees C. Both, temperature zinc alloying exhibit a pronounced influence on file saturation microstructure. The measurements reveal either a rate independent behavior of the Structural evolution at low temperatures and a rate dependent behavior of the Structural evolution at high temperatures. Two different processes are proposed to he the reason for the Saturation at low and hi-h homologous temperatures. [doi:10.2320/matertrans.MB200912]