The research of the rheological of the semi-solid Mg alloy

• Main Authors: Jun-Zhong Liao, 廖俊忠
• Other Authors: J. C. CHEN
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/kqp5u6

碩士 === 國立中央大學 === 機械工程研究所 === 94 === Abstract In this study, the rheological behavior of the semi-solid AZ91D magnesium alloy is researched by a high-temperature Couette type viscometer. The results show that the apparent viscosity of semi-solid AZ91D alloy decrease initially as the isothermal stirring time increase and achieve a minimum value and start increasing in steady state. And the different time of stirring before resting also affects striking on the apparent viscosity. The apparent viscosity was gradually increased as the resting time increased when the shorter stirring time. But the apparent viscosity gradually decreased as the resting time increased when the melt was isothermally stirred for the longer stirring time. And the solid fraction also has greatly influence the apparent viscosity. The apparent viscosity increases with increasing resting time as the higher solid fraction. And the apparent viscosity decreases with increasing resting time as the lower solid fraction. But it has not greatly influence the apparent viscosity when the very low solid fraction. At transient experimentation, the breakdown time is then described for a shear-rate jump from a lower shear rate to a higher shear rate and the recovery time is described for a shear rate drop from a higher to a lower shear rate. In this study, the recovery time is found to be longer than the breakdown time and the breakdown time is found to be longer at the higher solid fraction. The breakdown time is also found to be shorter as the range of the final shear rate jumps is big.