The thixotropic behavior of semi-solid AlSi6Mg2 aluminum alloy slurries was investigated through Couette type viscometer in the condition of isothermally stirring. The results show that apparent viscosity of the semi-solid AlSi6Mg2 aluminum alloy slurries is gradually declined to tend to a steady state with continuously cooling and isothermally stirring. However

the apparent viscosity of the slurries is rapidly increased and then quickly fallen down to a steady state value when stirring for the slurries is stopped at holding temperature for some time and then started again at some shearing rate

showing a typical shearing-thinning behavior. The longer the holding time is

the higher the apparent viscosity in initial shearing stage is and the longer the required steady state time is

meanwhile the steady apparent viscosity is slightly inclined. During isothermal shearing

the apparent viscosity will be declined or increased rapidly and then gradually declined to a steady state value with sharply raising or dropping shearing rate. The experimental results also show that the time required to reach a new steady state with sharply raising shearing rate is much shorter than that required with sharply dropping shearing rate.