Micro structures, tensile properties and corrosion behavior of die-cast Mg-4Al-based alloys containing La and/or Ce

In order to study the properties of Mg-Al-RE (AE) series alloys, the Mg-4Al-4RE-0.4Mn (RE= La, Ce/La mischmetal or Ce) alloys were developed. Their microstructures, tensile properties and corrosion behavior have been investigated. The results show that the phase compositions of Mg-4Al-4La-0.4Mn alloy consist of alpha-Mg and Al11La3 phases. While two binary Al-RE (RE = Ce/La) phases, Al11RE3 and Al2RE, are formed in Mg-4Al-4Ce/La-0.4Mn alloy, and Al11Ce3 and Al2Ce are formed in Mg-4Al-4Ce-0.4Mn alloy. The optimal tensile properties and corrosion resistance are obtained in Mg-4Al-4Ce/La-0.4Mn alloy, the excellent tensile properties are mainly attributed to fine grains and grain boundaries containing fine secondary phases, and the good corrosion resistance is partly related to the presence of compact corrosion product film containing Al and Ce/La. (C) 2007 Elsevier B.V. All rights reserved.