Rheological behaviour and fluidity of SiCp+AZ91HP magnesium composites

Abstract

Rotating cylinder viscosity and spiral fluidity experiments were carried out to investigate the effects of SiC particle fraction and size and casting temperature on the viscosity and the fluidity of Mg–8.2Al–0.7Zn (wt-%)alloy containing up to 10 vol.-%SiC particles. The rotating cylinder viscosity (process based viscosity) was deduced from the data measured by a power measurement system during the actual composite manufacturing by the rotating cylinder method, and the fluidity was measured using a specially designed spiral fluidity mould. The spiral fluidity, which is the reciprocal of viscosity, decreased with increasing SiC particle fraction (for a given size) and with decreasing SiC particle size (for a given volume fraction). Although the decrease in the fluidity of the composite slurry was observed due to the expected increase in the viscosity by the presence of SiC particles, the results showed that the fluidity of the composite slurry with 10 vol.-% 50 µm SiC particles was adequate to make a variety of castings at 680°C.