DEFORMATION, FRACTURE AND FATIGUE IN A DISPERSION STRENGTHENED ALUMINUM ALLOY

摘要

Numerous attempts to produce aluminum alloys that retain useful property levels after extended exposure to elevated temperatures have been made in the past two decades. The typical approach has been to create a fine grain material that is stabilized against grain growth by the presence of numerous dispersoids. The dispersoid composition is generally tailored so as to inhibit coarsening (either oxide dispersion or transition metal bearing intermetallics). This paper reports the fatigue, fracture, and tensile behavior of a dispersion strengthened alloy consisting of a nearly pure aluminum matrix reinforced by a few volume percent of Al_2O_3. The behavior of this alloy is compared to that of previously developed dispersion strengthened aluminum alloys. While the properties of the new material are reasonably good, it suffers from drawbacks similar to those exhibited by other DS-A1 alloys, notably reduced ductility with increasing temperature, low uniform elongation, minimal work hardening, and relatively low fatigue crack growth threshold at low stress ratio.