Thermal expansion

mechanical properties and microstructure of Al-20Si-1Ni-xMg alloys were described. The results reveal that

with 0.4% Mg content

thermal expansion coefficient of the high Si aluminum alloy modified by P and RE reaches 17.4×10-6/℃. The tensile strength of the alloy containing Mg can be greatly improved after T6 heat treatment

where the maximum value can be observed with approximately 0.4% Mg content

which is attributed to the precipitation of Mg2Si phase during heat treatment. Both primary Si phase and eutectic Si phase can be refined with P-RE compound modification

however

the Mg content has not obvious effects on P-modified primary Si phase. The fracture morphology of the high Si aluminum alloy is characterized by mixed rupture modes of ductile rupture of Al matrix and brittle rupture of Si particle.