The effect of isothermal mechanical stirring on an Al–Si alloy in the semisolid condition

Isothermal rheocasting studies were carried out on Al–5.2Si alloy under different processing conditions. The parameters varied are the shear rate, time of stirring, addition of grain refiner and the cooling rate. The addition of grain refiner prior to stirring has been found to influence the size and morphology of the primary particles. The shear rate–time combination has found to have tremendous effect in deciding the primary particle morphology. By proper selection of the processing parameters, globular primary particles can be obtained by mechanical stirring with a radial flow impeller in the semisolid range. The observed particle growth with increasing isothermal shearing time could be understood with the available theories of particle growth.