| dc.description.abstract | In this study, the flow behavior of the semi-solid AZ91D magnesium alloy is investigated by a high-temperature coaxial-cylinder viscometer. The relations between the steady-state apparent viscosity, shear rate and temperature of the magnesium alloy are observed. According to the results, the apparent viscosity decrease as the isothermal temperature and shear rate increase. The semi-solid AZ91D magnesium alloy shows the shear-thinning behavior. Basing on the experimental data, the power-law constant n is around 0.84. As the shearing time of maintained shear rate increase, the thixotropic behavior of magnesium slurry is more obvious. But the curve of reducing ratio is gradual, and the longer shearing time of maintained shear rate would not affect the shear stress. As the stirring time increases, the apparent viscosity initially decreases, and then it follows increasing curve. It is because that the dendritic structure is destroyed into the smaller non-dendritic one. As the stirring time continuously increases, the coarsening effect causes the particle size to increase. The solid fraction, pre-stirring time and resting time have influence on the flow behavior. When the pre-stirring time is fixed, the apparent viscosity increases as the resting time increases at high solid fraction. At the low solid fraction, the apparent viscosity decreases as the resting time increases. When the solid fraction is fixed, the apparent viscosity increases for shorter pre-stirring time as the resting time increases, and the apparent viscosity decreases for longer pre-stirring time as the resting time increases.
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