Creep Behavior of Extruded Sheets of Magnesium Alloys Containing La-Rich Mischmetal

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 (alpha)-Mg matrix, (beta) (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 (beta) 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.