The material used in the experiment is 7075 ultra-high strength wrought aluminum alloy. The solidus temperature is 477 ℃ and the liquidus temperature is 635 ℃. The temperature difference between liquid and solid phase is large, which is suitable for semi-solid forming. The sensitivity of solid ratio to temperature is also relatively low, which is beneficial to control the solid ratio in the preparation process of semi-solid slurry. 7075 is an Al Zn Cu mg super strength aluminum alloy, which can be heat treated and strengthened. It has been widely used in aerospace, shipbuilding, military industry, transportation, household appliances and other industries. The main problem of forming high strength aluminum alloy by traditional metal mold casting, gravity casting or pressure casting is the difficulty of mold filling and the tendency of hot cracking. Rheo squeeze casting will help to solve the above problems.
The main phase composition of 7075 aluminum alloy is α (AL), ƞ (mgzn2), s (Al2CuMg), t (al2zn3mg3), and the possible impurity phases are Mg2Si, Al (MnFe) Si, (Fe, Mn) al6, etc. The main strengthening phases formed by zinc and magnesium are ƞ and t. because of the high solubility of ƞ and T in aluminum, the strength of 7075 alloy is improved. The melting temperature of 7075 alloy is 700 ~ 750 ℃, the casting temperature is 685 ~ 700 ℃, and the thermal conductivity is 0.13kw · (m · ℃) – 1