The effect of carbon and silicon additions on the creep properties ofFe-40 at. % Al type alloys at elevated temperatures
Abstract
The mechanical properties of Fe-Al alloys with 39-43 at.% Al, C contents up to 4.9 at.% and Si contents up to 1.2 at.% were studied using uniaxial compressive creep at temperatures from 600 to 800 degrees C. The stress and temperature dependence of the creep rate were determined by stepwise loading and evaluated in terms of the stress exponent n and the activation energy Q, respectively.
These quantities can be interpreted by means of dislocation motion controlled by climb and by the presence of second-phase particles. The dislocation motion is obstructed by precipitates of carbide kappa in alloys E and F and by particles of Al(4)C(3) in the alloys with either higher content of C or of C and Si.
Both carbon and silicon improved the creep resistance, but the effect of silicon was more significant. (C) 2011 Elsevier Ltd. All rights reserved.