Effects of Low-Frequency Mechanical Vibration and Casting Temperatures on Microstructure of Semisolid AlSi8Cu3Fe Alloy

This paper is concerned with the influence of vibration on the cooling slope casting and gravity casting. Mechanical vibration during cooling slope casting is a new technique. Also isothermal holding period of hypoeutectic Al-Si alloy to prepare semisolid slurry has been studied. The convection caused by the vibration during solidification had remarkable effects on the formation of spherical alpha-Al particles. The main vibration effects include evolution and increase of nucleation and thus reducing as-cast grain size; globularization of particles and production of a more homogenous metal structure. In this work, mechanical mould vibration and mechanical-inclined plate vibration was applied to an AlSi8Cu3Fe alloy at fixed frequency. Metallographic examinations and grain analysis were done on specimens obtained with different pouring temperatures and casting methods. The alpha-Al particles were spherical in cooling slope casting under vibration, as compared with cooling slope casting without vibration and gravity casting with vibration. A grain analysis along with different casting techniques was performed in order to understand the vibration effect. A heat-transfer mechanism seems responsible for the vibration effect in grain formation.