Effects of solution treatment on hardness and microstructure of semi-solid squeeze casting A319 alloy were investigated.The characteristics of solution treatment semi-solid squeeze casting A319 alloy was analyzed.The results show that compared with metallic mold casting A319 alloy

semi-solid squeezing casting A319 alloy exhibits the features of low segregation degree and high solidification rate

where eutectic Al2 Cu phase is distributed along the grain boundary

and Q-Al5Cu2Mg8Si6 phase in form of eutectic and fine strip is distributed in grain boundary.The metallic mold casting A319 alloy exhibits serious segregation and low solidification rate

where Al2 Cu phase exists in the grain boundary and the matrix in form of block or mixed structure

and Q-Al5Cu2Mg8Si6 occurs in the grain boundary and matrix in form of dense block and rod.The morphology of phase contained Cu is inhibited in solid solution process.The phase contained Cu is more easily solved

so it needs a short solid solution time

exhibiting the solid solution features.It is feasible for semi-solid squeezing casting A319 alloy with solid solution at505 ℃for 3h.