Superposition of grain size and dispersion strengthening in ODS L12–(Al,Cr)3Ti

The preparation of oxide dispersion strengthened (ODS) Al67Cr8Ti25-type intermetallic compounds with L12-structure was carried out by mechanical alloying and ball milling. Subsequent powder consolidation by hot uniaxial pressing yielded fully dense samples with nano-scaled dispersions of 1–3 vol.% Y2O3, Al2O3 and CeO2 embedded in the single-phase matrix revealing a sub-μm grain size. As a single-phase reference, samples without oxide dispersions were also prepared. While retaining the mean dispersoid size, additional thermal and thermo-mechanical treatment yielded normal and abnormal grain growth of the matrix, respectively, to produce grain sizes ranging from several microns to close to 1 mm. Constant compression tests were carried out at ambient temperature to reveal the contribution to the yield strength stemming from the dispersoid/dislocation interaction as well as from dislocation pile-up at grain boundaries. The results are discussed in terms of actual microstructurally based concepts for room temperature yielding.