Comparison of Cu and Ti–52Al in creep at the same homologous temperature and minimum creep rate

The present work discusses conditions of comparable creep behaviour of a metal (copper) and an intermetallic compound (Ti–52Al). It compares three “similar” creep curves obtained at the same homologous temperature and showing the same minimum creep rate. In both materials, creep starts with an initial stage during which the creep rate decreases to its minimum. In the stage after the minimum, a remarkable difference in behaviour appears—a rapid tertiary stage in copper and a stage of a slowly increasing creep rate in the intermetallic alloy. Corresponding qualitative and quantitative differences in the dislocation structure and substructure resulting from pre-fracture creep were investigated by means of transmission electron microscopy.