High temperature creep properties of directionally solidified CM-247LC Ni-based superalloy

Abstract

This study explores the effects of cooling rate after solution heat treatment on the high temperature/low stress (982 degrees C/200 MPa) creep properties of CM-247LC Nickel base superalloy. Cooling rate was controlled by blowing argon gas, air cooling, and furnace cooling, which, in turn, gave rise to corresponding cooling rates (from 1260 degrees C to 800 degrees C) of 18.7, 7.4, and 0.19 degrees C/s, respectively. The results indicated that higher cooling rate from the solution heat treatment temperature led to finer gamma\' precipitates and much improved tertiary creep as well as rupture life time in high-temperature creep test. The microstructural analyses using both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that finer gamma\' precipitates and narrower gamma channel width could result in denser rafting structure which might have hindered the climb of dislocations across the precipitates rafts. (C) 2015 Elsevier B.V. All rights reserved.