Effect of equal-channel angular pressing on structural evolution, phase transformations and mechanical properties of Al-4Ca-0.8Mn-1.3Fe-0.1Zr-0.1Sc hypoeutectic alloy

Abstract

The effect of equal-channel angular pressing on structural phase transformations and mechanical properties of the as-cast hypoeutectic Al–4Ca–1.3Fe–0.8Mn–0.1Zr–0.1Sc alloy has been studied. ECAP was carried out under isothermal conditions at a temperature of 200 °C, with a channel intersection angle of 110º, using the BC route and the number of passes N = 6. After ECAP, a substructure with an increased dislocation density has developed in the alloy. ECAP led, firstly, to the evolution of the dendritic structure (dendrites elongate and merge with each other), and secondly, to the refinement of the Al4Ca, Al4Ca(Fe) and Al3−x(Fe, Mn) eutectic phase particles to nano- and submicron scale, their mixing and partial segregation of calcium. The tensile tests of the ECAP processed alloy showed that its strength increased, while its ductility decreased. The yield point increased from 122 to 257 MPa, the ultimate tensile strength increased from 174 to 281–314 MPa, and the relative elongation decreased from 6 to 1–3%. After ECAP, the strength is higher, and the relative elongation is lower for longitudinal specimens compared to transverse specimens.