Microstructure and tensile properties of AE42-based magnesium alloys with calcium addition

The as-cast microstructure of AE42 was of typical dendritic and composed of the a matrix and some needle-shaped interphases.Al11RE3. A small amount of Ca addition results in significant microstructural refinement and formation of a new phase A12Ca, which showed two kinds of morphologies, lamellar and tiny granular. The former distributes on grain boundaries and the later is within the matrix grains. With the increase of Ca addition the volume fraction of Al-RE compound (Al11RE3) decreases, but A12Ca increases. Addition of Ca causes a significant increase of yield strength of the alloy both at ambient and elevated temperatures, but a little decrease of the ductility. With calcium addition the ultimate strength decreases at ambient temperature and 150DGC, but increases at 175 deg C and 200DGC.