Creep behaviour of ultrafine-grained oxide dispersion strengthened copper prepared by cryomilling

The creep behaviour of ultrafine-grained (UFG) oxide dispersion strengthened (ODS) copper, containing 3 vol.% of yttrium and calcium oxides, respectively, was examined in the temperature interval of 500–700 °C at different deformation rates. Values of the Norton stress exponent n500 °C = 20 and n700 °C = 10 are near those of GlidCop (being essentially a alumina ODS Cu material). With two modifications introduced in this work, the creep behaviour can be described within the frame of the Rösler–Arzt diffusional creep model of thermally activated detachment of the grain boundary dislocations from the departure side of particles lying in or adjacent to grain boundaries. The relatively low values of around k ≈ 0.8 for both materials investigated give evidence for a strong interaction of grain boundary dislocations with the oxide particles and coincide nicely with k-values found for Y2O3 in the literature.