Aging behavior and microstructure evolution of a cold-drawn Ni-Co superalloy

Age hardening behavior and microstructure of superalloy AEREX 350TM in commercially cold-drawn condition were studied. It was found that aging the cold drawn alloy signicantly facilitated the formation of major phases of gamma prime and eta, in AEREX 350TM. Interestingly, the minimum temperature of formation of gamma prime and eta phases in the cold drawn alloy was lower by about 30C and 5C, respectively, to that previously reported for the solution treated alloy. Cold working, however, did not considerably in uence the maximum temperature of stability of these phases. In addition, Widmanstatten morphology of eta phase signicantly improved in the cold drawn samples compared to that seen in the solution treated alloy. Diusion through dislocation network could have facilitated growth of major phases whereas its in uence on dissolution temperature of these phases was negligible. In addition, it was suggested that cold working might increase the density of hcp nuclei in the fcc matrix. This may justify the observed enhancement of the Widmanstatten morphology of eta phase in these samples following the aging process