Effect of eutectic temperature on the extrudability of magnesium–aluminum alloys

The limited extrudability of AZ31 (Mg–3Al–1Zn) alloy is reported to be caused by incipient melting of the Mg17Al12 binary phase with a eutectic temperature of 438 °C. Computational phase equilibria and microstructural examination, however, show that Mg–Al–Zn ternary phases with eutectic temperatures as low as 338 °C are actually present in the AZ31 alloy, which is indeed the real limitation to its extrudability. The significantly improved extrudability of AM30 alloy (Mg–3Al–0.3Mn) is due to the absence of these zinc-containing eutectic phases.