Magnesium alloy components are normally manufactured by
high-pressure die casting (HPDC) process because of good dimensional
accuracy, high production efficiency, and considerable
economic benefit. However, because of the nucleation in shot
sleeve, fast filling speed and high cooling rate in HPDC process,
various defects like gas pores (air entrapment), shrinkage pores
(solidification contraction), defect band and externally solidified
crystals (ESCs) exhibit in the final microstructure of die castings
[1–5], which greatly decreases the final mechanical properties of
the components.