Rheological Properties and Microstructure of Hypereutectic Semi-Solid Al-Si-Mg Alloys Using Rheocasting Route

Abstract:

The SEED rheocasting process was used to produce semi-solid slurries of hypereutectic Al-17Si-4.5Cu (A390) and Al-15Si-10.5Mg-4Cu alloys respectively. The rheological properties of these alloys in the semi-solid state were characterized at different deformation rates and at variable solid fractions using the parallel plate compression viscometry. The viscosity at different shear rates was calculated using a Newtonian fluid model for increments of deformation during compression. Microstructures of both alloys, after partial solidification and compression, were examined in order to characterize the flow behavior during deformation. The comparison of the viscosity between the A390 and Al-15Si-10.5Mg-4Cu alloys indicated that the high Mg containing alloy possessed a higher viscosity for the range of shear rates and solid fractions investigated. Rheological results showed that at a given solid fraction, the viscosity of both alloys decreased significantly with increasing shear rates, indicating a shear thinning behavior. In addition, a separation of liquid and solid phases was also observed for both alloys in the microstructural study of compressed semi-solid billets.

• Periodical: Solid State Phenomena (Volumes 192-193)
• Pages: 323-328
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.192-193.323
• Online since: October 2012
• Authors: Mehand Tebib, Frank Ajersch, X.-G. Chen
• Keywords: Hypereutectic Al-Si-Cu-Mg Alloy, Microstructure, Rheocasting, Rheological Property, Semi-Solid Metal

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