Modeling of oxide dispersions in reactively processed al

Abstract

The present article reports on the formulation of an analytical model to predict the size scale of oxide dispersoids in Al alloys processed by a reactive atomization and consolidation synthesis approach. The proposed model formulation is primarily based on the assumption that all of the strain energy in the oxides is used to create interfaces between the oxide dispersoids and the matrix. The following predictions are made, based on the preceding analytical model. First, the diameter or thickness of oxide discs (the oxide dispersoids are assumed to have a disc geometry) constantly decreases with increasing strain. However, when exposed to the range of strain levels that are present in conventional processes (e.g., less than 100:1, 90 pct, and 90 pct of area, thickness, and height reduction ratio in extrusion, rolling, and forging, respectively), the oxide discs will fracture into sizes that are on the order of tens of nanometers in both diameter and thickness. Ultra-high strain levels (e.g., more than 18.5 of total strain) are required to obtain ultra-fine oxide discs whose diameter and thickness are on the order of nanometers. Second, working temperature appears to exert only limited influence on the final diameter or thickness of the oxide discs. The size scale of oxide dispersoids predicted on the basis of the analytical model presented herein is in good agreement with the available experimental observations.