Grain boundary precipitation strengthening in high temperature creep of Fe15Cr25Ni alloys

Abstract Grain boundary carbide precipitation gives rise to a dramatic decrease in creep rates compared with those of a single phase alloy. The high stress exponent (n=7) and creep activation energy (Q C > Q sd ) have been found due to these intergranular carbides, indicating that they both increase creep resistance and change creep characteristics of alloys. The model present here rationalizes the observed behavior in single phase and two phase alloys with grain boundary carbides by a unified power law equation involving boundary obstacle stress. The predictions of this model are in close agreement with experimental results.