A magnesium based alloy consists of, by weight: 1.4-1.9% neodymium, 0.8-1.2% rare earth element(s) other than neodymium, 0.4-0.7% zinc, 0.3-1% zirconium, 0-0.3% manganese, and 0-0.1% oxidation inhibiting element(s) the remainder being magnesium except for incidental impurities.