The influence of ageing
precipitation particles containing copper on the yield strength, the size distribution of precipitates,
and the blocking effect of the precipitates on dislocation slips in high purity Fe-1.03 wt% Cu and Fe-1.65 wt% Cu alloys were observed and investigated. The quantitative relationship between
precipitation particles and yield strength was analyzed based on Frank-Read
strengthening theory. It is found that the precipitation particles belong to a meta-stable Cu-Fe phase containing certain iron and have the ability to be deformed, which leads to a high ductility combined with high yield strength. However, the precipitation particles containing copper are not rigid particles, and therefore have lower strengthening effect than those of conventional rigidity compound particles. On the other hand, the precipitation particles containing higher iron will enhance the volume fraction of precipitates and therefore the strengthening effect. The blocking effect on dislocation slips as well as the corresponding yield strength can be increased with increasing copper content in the precipitation particles.