Microstructure and mechanical properties of spray deposited and extruded/heat treated hypoeutectic Al–Si alloy

Abstract

The microstructure and the tensile properties of an Al–8.9 wt.% Si–3.2 wt.% Cu–0.9 wt.% Fe–0.8% Zn alloy processed by spray forming was investigated. The porosity level, the conditions of the heat treatment applied and the presence/addition of certain alloying elements to this alloy is known to greatly affect its mechanical properties. In this work, the alloy was gas atomized with argon and deposited onto a copper substrate, extruded at 623 K and heat treated to the T6 temperature Mg was added to some heats. Room temperature tensile tests of the spray formed and extruded alloy showed significant increase of elongation when compared with the values observed for the as-spray formed deposits. This result can be ascribed to the decrease of porosity promoted by the extrusion process. The spray formed and extruded, T6 heat-treated samples showed significant increase of strength without lowering the elongation results. The addition of 0.3 wt.% Mg increased the response to the heat treatment process.