半固态A356铝合金流变特性研究

用自行研制的同轴圆柱旋转流变仪对半固态A356铝合金浆料的流变特性及组织演变进行研究.结果表明:等温剪切时,浆料稳态表观粘度随着剪切速率的增大而下降,半固态A356铝合金具有明显的触变性.在连续冷却条件下,半固态浆料的表观粘度随着温度的降低而先缓慢后迅速增大,冷却速度显著影响半固态A356铝合金的表观粘度,降低冷却速度,由于搅拌充分而导致表观粘度明显下降.显微结构分析也可以反映出剪切速率、温度和冷却速度对表观粘度的影响规律.

Investigation on the Rheological Behavior of Semi-Solid A356 Aluminum Alloy

The rheological behavior and microstructure of the semi-solid A356 Aluminum alloy slurry were studied by using a self-designed viscometer. The results show that the apparent viscosity of A356 alloy slurry in steady-state decreases with the shear rate increasing under isothermal shearing condition. The flow behavior of the semi-solid state A356 alloy possesses obviously thixotropic. During the continuous cooling at a constant shear rate, the apparent viscosity slowly increases originally and then sharply with temperature decreasing. It has a sharp dependence on the cooling rate. Decreasing the cooling rate will low the apparent viscosity. The analysis of microstructure can also reflect the regulation of the effect on the apparent viscosity of factors, such as shear rate, temperature and cooling rate.