Role of dislocation density in raising the stage II work-hardening rate of Alloy 625

In contrast to the general work-hardening (WH) behavior of a polycrystalline fcc material, increase in the work-hardening rate is observed in Alloy 625 following precipitation of Ni2(Cr,Mo) and γ″ phases. A typical stage II WH behavior of an fcc single crystal is seen in this alloy, before and after the precipitation. Appearance of such WH behavior is attributed to the domination of planar slip during deformation. TEM results from samples, before and after deformation, indicate that the precipitates are coherent or semi-coherent in nature and hence, partially or fully dissolved due to repeated shearing by dislocations. A gradual increase in WH rate of the alloy due to aging appears to justify the role of various types of geometrically necessary dislocations, which are formed as a result of precipitation.