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

抄録

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.