New interpretation of the Haasen plot for solute-strengthened alloys

The Haasen plot (inverse activation area 1/Δa vs. offset flow stress σ–σs) for solute-strengthened alloys is usually assumed additive, 1/Δa = 1/Δas + 1/Δaf, with 1/Δaf ∼ β(σ–σs) due to forest interactions. Experiments often show a slope <β. Here, a model for the dislocation activation enthalpy is proposed that predicts a slope 1/(Δasσs) determined only by solute parameters Δas and σs and not directly connected to forest hardening. This parameter-free prediction agrees well with a wide range of experiments on Al–X alloys at T = 78 K.