On the creep behaviour of Ni based binary solid solution alloys

Although it was widely accepted that the creep rate of a material influenced by the stacking fault energy, there is a considerable ambiguity in the relationship between these parameters, especially in solid solution alloys. To address this issue, the f.c.c. based binary Ni – x Co (x = 10, 33, and 60 at%) alloys were considered in the current study. All alloys showed dislocation climb controlled creep behaviour in the observed temperature and stress range. The creep deformation resulted in the microstructural changes such as cell formation, dynamic grain growth and detwinning in these alloys. Owing to the lowest stacking fault energy value, the creep rates of Ni – 60 Co were observed to be the lowest among all alloys. Interestingly, no pronounced difference in the creep rates were observed between Ni – 10 Co and Ni – 33 Co alloys despite their different stacking fault energies. A comparison between the creep rates of binary Ni – Co alloys from the present study with f.c.c. based binary solid solution alloys from the literature suggested a possible parameters or factors for the uncertain relation between the creep rate and stacking fault energy in the dislocation climb controlled region.