New aluminum-calcium casting alloys based on secondary raw materials

Abstract Phase equilibria in the Al-Ca-Cu system and the microstructure, mechanical and casting properties of the alloys were investigated. We show that the most promising alloy composition is up to 3 wt% Ca, 0,5 wt% Cu and 1,5 wt% Mn (Al3Ca0,5Cu1,5Mn). The microstructure consists of Al primary crystals and ultra-fine eutectic colonies formed by submicron-size intermetallic particles (Al4Ca), with copper solution being present in both structural components. Uniaxial tensile tests of as-cast promising Al3Ca0,5Cu1,5Mn alloy revealed an ultimate tensile strength of about 188 ± 5 MPa, a yield strength of 144 ± 3 MPa and a ductility of 7.5 ± 1.4%. The possibility of the formation of shrinkage defects in the as-cast alloys was estimated by measuring the index of hot tearing tendency and casting shrinkage coupled by solidification range. The mechanical and casting properties of the new alloy are comparable to those of the conventional A356 alloy.