By hardness and tensile testing

optical microscope

scanning electron microscope and transmission electron microscope

the effects of different heat treatment processes on the microstructure and mechanical properties of high pressure diecasting（HPDC） AlSi10 MnMg alloy shock tower were investiagted. The results indicate that T5 and T6 heat treatment can improve the microstructure and mechanical properties of the shock tower. After T5 heat treatment

the silicon phase in the structure is spheroidized

and the plasticity of the shock tower is increased with the increase of heat treatment temperature. After T5（350 ℃×2 h） heat treatment

the elongation reaches 16.32%

which is twice of that of the as-cast state. After T6 heat treatment

the Mg

2

Si and other strengthening phases can be precipitated

however the size is increased with the increase of temperature

while the strength of shock tower is decreased continuously with the rise of the temperature. After T6（500 ℃×2 h+175 ℃×6 h） heat treatment

the yield strength

tensile strength and elongation of the shock tower reach 217.06 MPa

294.28 MPa and 10.25%

respectively.