Dislocation Creep in Magnesium

Abstract

A comparison of the creep behaviour of sintered magnesium powder and magnesium prepared by conventional methods has been made. Sintered material has a higher strength and quite different creep characteristics, which have been attributed to the presence of a magnesium oxide particle dispersion. Re-examination of all the existing creep data for pure magnesium has indicated that above ∼ 350° C creep occurs with a high activation energy (∼ 230 kJ/mol, 55 kcal/mol), and a high stress exponent (∼ 10),probably corresponding to non-basal cross-slip. Below 350° C creep occurs with an activation energy close to the likely value for dislocation pipe diffusion (∼ 92 kJ/mol, 22 kcal/mol), and with a stress exponent of ∼ 5.