Al-20%Mg2Si composite was in situ synthesized and modified by the addition of Ba and Bi;
the microstructure of the resulting composites will be investigated. It is expected that the comodification
with Ba and Bi effectively refined the morphology of Mg2Si which is attributed to the
formation of fine Ba2Bi particles that acted as the heterogeneous nucleation sites for the primary Mg2Si
particles, resulting in a refined distribution of these precipitates. Therefore, the addition of Ba and Bi
can provide a better effect than only the addition of Bi or Ba separately.