Evaluation of fluidity of semi-solid aluminum alloy slurry prepared by mechanical vibration

摘要

The semi-solid process is viewed as an attractive near net-shape method for producing light metal products with reduced porosity and shrinkage. However, the semi-solid process has the disadvantages of poor formability by low fluidity, and a difficulty of preparation of semi-solid slurry. In this study, we have developed a new method to prepare the semi-solid aluminum alloy slurry by applying mechanical vibration. Then the fluidity of this slurry was evaluated by using high pressure die casting (HPDC) machine. Moreover, compared to the slurry made by the electromagnetic stirring method which is commonly methods to make the high quality slurry. In the result, the fluidity of slurry was increased by applying shear stress. Then the slurry made by mechanical vibration had enough fluidity. Moreover, the solid particles in the slurry, which were observed as primary a-phase, became small and fine with increasing shear stress. This result is considered the cause of decreasing viscosity of slurry and increasing fluidity. At low shear stress region, the fluidity of slurry made by applying mechanical vibration is lower than made by the electromagnetic stirring method. However, the fluidity of mechanical vibration method slurry increased to approximately equivalent to electromagnetic stirring method slurry by applying high shear stress.