2006 Volume 47 Issue 2 Pages 433-439
In this study, the effect of RE content on the microstructure and creep properties of Mg–8Al–xRE (x=0, 1, 2 or 3 mass%) alloys were investigated. The microstructural analysis and phase characterizations of Mg–8Al alloy with 1–3 mass% RE (La-rich Mischmetal) additions were conducted. (i) The as-extruded Mg–8Al–xRE alloys consisted of an α-Mg matrix, β (Mg17Al12) and Al11RE3 compounds. (ii) Raising the extent of RE in the alloy also increases the amount and coarsening of the Al11RE3 compounds, but the amount of β phase diminishes and turns into the fine particles. The creep rupture life increment measured at 423 K is around 40–100 MPa, and the creep rupture life over 423 K is also prolonged. The marked improvement in high-temperature tensile creep properties is attributed to the fine rod-like Al11RE3 compound having high thermal stability in the alloys.