Open-cell superalloy foams via the combined electrolytic-suspension route

Low-density open-cell nickel foams were prepared by electrolytic replication of polyurethane foam. Then, the sintered products were impregnated with the 625 superalloy powder suspension. The final foam density could be controlled by number of impregnations. Then the foams were sintered in vacuum. The foam microstructure and distribution of alloying components (Cr, Nb and Mo) were dependent on the sintering temperature, which, in its turn, effected mechanical properties of the foams (the shape of the stress-strain curve and the yield stress). Complete densification of the powder layer was attained at temperatures close to the superalloy liquidus point, i.e. at 1320-1335^oC. Addition of a mixture of Ni, Cr and Mo fine powders to the superalloy powder suspension favored the powder layer densification, ensured more uniform distribution of alloying elements and improved mechanical strength.