| Abstract: | It is shown in this paper that the hardening of Cu-Ti and Cu-Ti-Al alloys at the coherent-decomposition stage can be described in terms of the basic Mott-Nabarro mechanism. The overaging stage in Cu-Ti alloys is due to the partial loss of coherence of the  -phase, though cutting of the particles by dislocations continues. In Cu-Ti-Al alloys bypassing of the particles in the way suggested by Orowan offers a possible deformation mechanism at the overaging stage. These conclusions are supported by the slip patterns obtained by electron microscopy of replicas. The small difference between the slip patterns of specimens having been quenched and those having been aged to give maximum mechanical properties should be particularly noted, since it is at variance with the data already available, mostly from aluminum alloys. |
