The following conclusions could be drawn from the current work:
1. Calcium additions refine the microstructure of AZ91 alloy and form
Al2Ca lamellar secondary phase to replace Mg17Al12 phase on grain
boundaries. Excessive calcium additions degrade the mechanical
properties and elongation.
2. The advantageous manufacturing process of liquid forging and extrusion
further refines the microstructure and provides work hardening,
and hence improves the mechanical properties significantly.
3. 2% calcium addition to AZ91 alloy has increased the ignition point to
above 800 °C, and its strength and elongation are excellent after liquid
forging and extrusion.