Effects of pouring temperature and solid solution temperature on the microstructure and mechanical properties of Al-6.8Zn-2.5Mg-2.0Cu alloy prepared by squeeze casting were investigated by tensile testing

OM（optical microscopy）

SEM（scanning electron microscopy）and XRD（X-ray diffraction）.The results show that compared with that in metal mold gravity casting

microstructure of the squeezing casting alloy can be refined significantly with decrease of the shrinkage defects

which are responsible for the improvement of mechanical properties.The primaryα-Al grain sizes are increased with the increase of pouring temperature in metal mold gravity casting

while their are decreased at first and then increased with the increase of pouring temperature in squeeze casting with the pressure of 60MPa. With pouring temperature of 720℃

the secondary dendrite arm spacing（SDAS）of the alloy reaches minimum size of about 26.3μm

and tensile strength and elongation of the castings reach 310MPa and 4.0%

respectively.After solution treatment at 470℃for 10hand aging at 130℃for 24h

the tensile strength and elongation of the castings reach 590 MPa and 4.7%

respectively

obtaining desirable strengthening-toughening effects.