Effect of La content on microstructure, thermal conductivity and mechanical properties of Mg–4Al magnesium alloys

Abstract

Microstructure, thermal conductivity and mechanical properties of Mg–4Al-xLa (x = 2, 4, 6 wt%) were investigated. The concentration of Al dissolved in α-Mg matrix decreases with the increase of La content, and the volume fraction of Al11La3 in the Mg–4Al-xLa alloys increases because La tends to consume Al to form Al11La3. As a consequence, both yield strength and thermal conductivity of the Mg–4Al-xLa alloys in as-cast condition increase with the increasing La content. After extrusion, both thermal conductivity and mechanical properties of the Mg–4Al-xLa alloys further increase due to dynamic precipitation of Al11La3 which consumes the Al solutes dissolved in the α-Mg. The extruded Mg–4Al–6La alloy exhibits high thermal conductivity of 130 W/m·K, ultimate tensile strength (UTS) of 337 MPa, yield strength of 256 MPa and elongation to failure of 8.4%.