Thermal Stability of the Structure and Mechanical Properties of Submicrocrystalline Al–0.5% Mg–Sc Aluminum Alloys

The thermal stability of the grain structure, the mechanical properties, and the electrical resistivity of submicrocrystalline (SMC) Al–0.5% Mg alloys with 0.2, 0.3, 0.4, and 0.5% Sc is studied. The alloys are fabricated by induction casting and equal-channel angular pressing (ECAP). The alloys with >0.3% Sc contain submicrometer primary Al3Sc particles, the amount of which increases with the scandium content in the alloys. The precipitation kinetics of Al3Sc particles in the SMC alloys is determined by the intensity of diffusion processes along lattice dislocation cores and grain boundaries. ECAP of the alloys at a temperature of 225°C provides high thermal stability of the SMC structure: the temperature of the onset of recrystallization is 375°C. At room and elevated temperatures, the SMC alloys have a high plasticity and a good combination of strength, hardness, and electrical conductivity.