Creep properties at 125 °C of an AM50 Mg alloy modified by Si additions

The creep behaviour of an AM50 alloy modified by the addition of different proportions of Si was investigated at 125 °C. Increases from 0.3 to 1.5 wt.% Si led to a significant reduction in secondary creep rate. The time to rupture under 100 MPa increased with Si content and peaked with Si = 0.5 – 0.8 wt.%; further increases in Si content did not induce significant variations in creep strength, since the reduction in creep rate was offset by a parallel reduction in ductility. Microstructural investigations led to the identification of the major strengthening phases: β-Mg Al and Mg Si. Results are discussed and analysed in the light of the more recent data on the creep response of other Mg– Al alloys.