Dispersion strengthened alloys are known to have extremely high stress exponent and activation energy for creep deformation which cannot be explained by the typical dislocation climb controlled model. Recently, the motion of dislocations in the dispersion strengthened alloys under creep has extensively been analyzed in terms of the attractive dislocation-particle interaction.
In order to improve the models for the dislocation detachment controlled creep in the dispersion strengthened alloys, the creep behavior of an Al-Fe-V-Si/$SiC_p$ composite has been analyzed based on the attractive dislocation -particle interaction with the assumption that the optimum particle radius is not a constant value but increases with increasing temperature.
The size of the SiC particulates is so large that they cannot be related to the dislocation detachment process because the relaxation parameter approaches to 1. Hence, the detachment controlled creep rate may mainly be determined by the interaction between dislocation and $Al_{12}(Fe,V)_3Si$ dispersoids. The calculated creep rates are shown to be in good agreement with the experimental data at various temperatures. The model can also properly explain why the value of the stress exponent and the creep strength of the composite decrease with increasing temperature.
The suggested model can also interpret the creep behaviors of other dispersion strengthened alloys produced by rapid solidification process and mechanical alloying.
Creep equation has been modified to more clearly explain the creep behavior of dispersion strengthened alloys. Using the modified creep equation, the normalized creep rate can be shown on a single line when plotted against the stress normalized by the detachment stress. That is, if the stress normalized by the detachment stress are same, then the normalized creep rate will also be the same for the various dispersion strengthened alloys.
