**4. Conclusion**

The addition of 0.1 wt% Sc exhibits the highest fluidity in all cross-sections ranging from 0.5 to 8 mm thicknesses whereas V addition shows the lowest fluidity.

Although, the microstructural changes are not so significantly different from each other (all additions have SDAS values in the range of 30–40 μm), in terms of tensile properties, Sc addition to A357 alloy reveals the highest reliable and reproducible results. On the other hand, Y additions have the highest scatter with being the lowest reliable.

Before heat treatment, almost all additions have yield stress in the range of 119–130 MPa and ultimate tensile strength between 180 and 210 MPa. The addition of 0.1 wt% Sc has the highest UTS of 218 MPa which is quite closely followed by 0.1 wt% Er with a value of 212 MPa. Similarly, elongation at fracture values lie between 3.6 and 4.6% where Y is the lowest and Sc and Er is the highest.

After heat treatment, there are approximately two folds of increase in the yield strength for all additions. Y is the lowest with 210 MPa, and Sc and Er are the highest with 260 and 240 MPa, respectively. There is an approximately a 30% increase in UTS after heat treatment. Er is the highest with 300 MPa, followed by Sc at 299 Mpa. Y is the lowest with 240 Mpa. Elongation at fracture values were decreased dramatically after heat treatment from 4% towards 1%. Er shows the highest elongation with 4.9% while Y is the lowest with 1.2%.

In almost all additions, toughness value decreased after heat treatment, however, only when 0.1 wt% Er was added to A357, there was no difference in the toughness before and after heat treatment.

*Characterization of Casting Properties of Rare-Earth Modified A356 DOI: http://dx.doi.org/10.5772/intechopen.101722*
