Mechanical properties and creep of Mg – rare earth – Sc – Mn squeeze cast alloys

The microstructure developed during the T5 treatment of squeeze cast magnesium alloys containing rare earth (Gd, Y, or Ce, ≈ 3–10 wt.%), Sc (< 1 wt.%) and Mn (< 1.5 wt.%) is responsible for a reasonable age hardening in MgGdScMn alloys. Moderate age hardening is only possible in MgY4Sc1Mn1 or MgCe3Sc1Mn1 alloys. The c‐based centred orthorhombic phase precipitating as fine prismatic plates in a triangular arrangement is the most effective hardening phase. The stability of yield strength up to 250°C–300°C was confirmed in T5 treated MgGdScMn and MgY4Sc1Mn1 alloys. All alloys exhibit a reasonable ductility at room temperature. The precipitation of very fine basal discs of Mn₂Sc phase observed in all T5 treated alloys investigated does not contribute considerably to the hardness, but it is very effective in restricting creep. The creep resistance of all alloys investigated is superior to that of commercial WE54 alloy up to 350°C.