Constitutive modeling and microstructure characterization of Al-30at.%Sc intermetallic compound during high temperature deformation

To explore the hot-deformation mechanism of Al with high-content Sc, an Al-30at.%Sc intermetallic compound is prepared via high-vacuum arc melting. Isothermal hot-compression (1000–1100 °C, 0.001–0.1 s⁻¹) yield true stress-strain curves, and an Arrhenius-type constitutive equation is derived. A hot-processing map is constructed based on the dynamic material model. The physical property data of Al-30at.%Sc intermetallic compound (varying with temperature) was calculated and constructed, and successfully applied to the Deform-3D software platform in combination with its constitutive equation. Results show that the hot-deformation activation energy at the peak stress, and at a strain of 0.3 is 421.1 kJ/mol, and 431.8 kJ/mol, respectively, which produces a correlation coefficient of 0.98 between predicted and experimental true stress and the peak power-dissipation factor ∼0.58. Grain size increases with rising deformation temperature or decreasing strain rate. Nanoscale observation reveals different dislocation structures and strain-field concentration areas under various thermal-deformation conditions. Al₃Sc and Al₂Sc precipitated phases are formed in the Al-30at.%Sc intermetallic compound. The L1₂-type ordered structure of the Al₃Sc phase blocks dislocation movement, causing pile-up and complex dislocation morphologies. The elastic-modulus difference between Al₂Sc and Al₃Sc phases leads to uneven stress and strain-field concentration.