Interaction of dislocations with precipitates in a Cu–Be–Ni–Zr alloy

Abstract

The interaction of dislocations with precipitates in an age-hardened polycrystalline alloy (the total amount of alloying elements is about 2 wt-%) is reported. An electron microscope study of thin foils aged similarly to the tensile-test specimens reveals that during aging between 450° and 600°C a precipitation sequence exists: GP zones – metastable coherent particles – non-coherent particles of a stable phase. The presence of GP zones and coherent particles increases the yield stress but has little effect on work-hardening characteristics. Precipitation of non-coherent particles initiates high work-hardening rates. The high yield stress of the zone-containing alloy is owing to the work done in forcing the dislocations through the zones. The high work-hardening rate of the specimens containing non-coherent particles suggests that the dislocations do not cut through particles, but avoid them.