Precipitation hardening in dilute Cu-Ti alloys

Conclusion

Summarizing we can conclude that:

• 1) At the state of the maximum CRSS, that is in the state of quasiregular arrangement of precipitates, the proposed theory gives satisfactory results in all considered cases.

• 2) This simple theory explains also satisfactorily hardening during ageing in regime III, but only for (a) and (c) concentration regions.

• 3) On the basis of presented calculations it seems that edge dislocations rather than screw ones are controlling the initiation of deformation at least with respect to CRSS.

• 4) Finally, the Ti concentrations (c < 1·3 at% Ti) are sufficiently low to admit tunnelling through a regular array of obstacles. This effect could be a possible reason for overageing observed in regime IV. In fact, for specimens with higher concentration, e.g. 1·6 at% Ti, no overageing has been observed up to 850 hours [14].