The elevated temperature creep properties of a fine grained copper alloy (CDA 638) was investigated between 673 and 798 K at strain rates ranging from lo-' s-' to 2 x lo-* s-'. The mechanical data were analyzed in order to establish the stress, temperature, and grain size dependence of the strain rate. The double logarithmic plot of stress vs strain rate at constant temperature and grain size revealed four distinct regions. It is suggested that the rate controlling deformation mechanisms for these four regions are, in terms of increasing strain rate values: region I, dislocation climb controlled creep; region II, a transition from climb-controlled to viscous glide controlled creep; region IIIA, viscous glide controlled creep. and; region IIIB, a transition region from viscous glide creep to obstacle-limited glide in the so-called "Power Law" breakdown regime.
RPsum&--Le fluage a la temperature elevte dun alliage de cuivre (CDA 638) ri grains fins a Ctt etudie entre 673 et 798 K pour des vitesses de deformation comprises entre 10-6s-' et 2 x 10-2s-'. La