Effect of secondary phase on mechanical and thermal conductivity of Al-Si-xFe-Mg-yCu-Mn die casting alloys

Abstract

In the present study, effect of secondary phase on mechanical property and thermal conductivity of newly developed high-pressure die-cast Al-6Si-0.3Fe-1.5 Mg(S-1), Al-6.5Si-0.4Fe-1.6 Mg-0.7Cu-0.08Mn(S-2), and Al-8Si-0.5Fe-0.5 Mg-1.5Cu-0.10Mn-0.1Ni(S-3) alloys were investigated. The fraction of α-Al phase and secondary phase has been predicted by thermodynamic simulations. UTS was found to be 307 MPa, 331 MPa and 350 MPa for S-1 ∼ 3 alloys. The thermal conductivities values are 160.3 W/mK, 153.0 W/mK, and 146.0 W/mK for S-1 ∼ 3 alloys. The S-3 alloy has the highest fraction of the secondary phases and as a result of the addition of Fe and Cu is partially precipitated into the Al5Cu2Mg8Si6, Al7Cu2M and β-AlFeSi phases. The mechanical properties of these alloys were found to be directly proportional to the fraction of Si addition as well as secondary phases, whereas thermal conductivity shows the opposite trend. Newly developed S-3 alloys in the present study showed excellent mechanical and thermal conductivity as compared to other Al alloys reported in the literature.