Thixotropic behavior of semi-solid AZ91D magnesium alloy①
(School of Materials Science and Engineering,
University of Science and Technology Beijing, Beijing 100083, China)
University of Science and Technology Beijing, Beijing 100083, China)
Abstract: The thixotropic behavior of semi-solid AZ91D slurry was studied through a Couette type viscometer. The results show that the apparent viscosity of semi-solid AZ91D magnesium alloy slurry increases after being isothermally held, but the apparent viscosity quickly falls down to a steady state value after being stirred again and it takes on a sharp shear-thinning behavior. With the same shearing rate and the rest time increasing, thesteady apparent viscosity increases because of the agglomeration of thesolid particles, and the time required for the slurry to reach the steady state also becomes longer. If the solid fraction increases, it takes longer time for the slurry to reach the steady apparent viscosity with the same shearing rate and the same rest time. If the solid fraction and the rest time are the same, but the shearing rate rises, it takes shorter time for the slurry to reach the steady apparent viscosity and the final steady apparent viscosity also decreases.
Key words: magnesium alloy; AZ91D; thixotropic behavior; semi-solid; apparent viscosity