The determination of solute clusters in dilute aluminum alloys using strain rate sensitivity

Precise, apparent activation volumes, V′, are determined at 78 K for aluminum solvent systems containing mostly Fe, Cr, Cu or Mg in solution. The relationship between 1/V′ and the flow stress correlates to the amount of solute in the aluminum matrix. It appears that only Fe solute manifests solute-defect interaction effects which approximate a random solid solution. All other solute elements exhibit a much reduced distribution of strain centres, suggesting that these solutes are clustered even though the dilute alloys were solutionized at temperatures considerably above the solvus temperature. Stress equivalence of the apparent activation volume is observed over a range of yield stress, σ0, as V′ ∝ σ0−0.95.