Precipitation of Al3Sc in Al-0.23 mass%Sc alloy

Abstract

Age hardening and precipitation processes in an Al-0.23 mass%Sc alloy were studied by the hardness test, electrical resistivity measurement and TEM observation. The stable and coherent Al3Sc phase of the Ll2 ordered structure precipitates directly from a supersaturated solid solution without forming any metastable phases. A plot of the cube of the particle radius against aging time follows a straight line, suggesting that the coarsening obeys the LSW theory of the diffusion controlled ripening process. The apparent activation energy for the precipitation of the Al3Sc phase determined by electrical resistivity change is 80 kJ/mol.