The effect of thermal exposure on the properties of a Ni-base superalloy

The effect of 1000 h thermal exposure on the microstructural instability and mechanical properties degradation of IN738C at 850 °C were investigated by means of TEM, SEM and accelerated creep tests. Experimental observation on the coarsening of primary and secondary γ′ precipitates showed that D 3 − D 0 3 is linear with time in accordance with LSW theory. The correlation between γ′ changes due to thermal exposure and creep characteristics was investigated and modeled on the basis of the γ′ diameter and γ′ particles spacing.