Experimental Study on Viscosity and Phase Segregation of Al-Si Powders in Microsemisolid Powder Forming

TitleExperimental Study on Viscosity and Phase Segregation of Al-Si Powders in Microsemisolid Powder Forming
Publication TypeJournal Article
Year of Publication2010
AuthorsWu YF, Kim GY, Anderson IE, Lograsso TA
Journal TitleJournal of Manufacturing Science and Engineering-Transactions of the Asme
Date Published02/01
ISBN Number1087-1357
Accession NumberISI:000274524200003
Keywordsaluminum-alloy, back extrusion, composites, deformation, design of experiments, finite-element-analysis, forming processes, mushy zone, powder technology, rheological behavior, semisolid state, shear rates, sn-15 pct pb, VISCOSITY

Semisolid powder forming is a promising approach for near-net shape forming of features in macro-/microscale. In this paper, viscosity and phase segregation behavior of Al-Si powders in the semisolid state were studied with back extrusion experiments. The effects of process parameters including shear rate, extrusion ratio, heating time, and precompaction pressure were analyzed using the design of experiments method. The results showed that the effects of shear rate, extrusion, ratio and heating time were statistically significant factors influencing the viscosity. The semisolid state powders showed a shear thinning behavior. Moreover, microstructure analysis of extruded parts indicated severe phase segregation during the forming process. As the extrusion opening became small (similar to 400 mu m), the phase segregation increased. This study expanded the semisolid processing technology by exploring the use of powdered materials instead of typical bulk materials for applications in micro-/mesomanufacturing. Replacing bulk materials with powdered materials may add a new dimension to the technique by allowing tailoring of material properties.

URL<Go to ISI>://000274524200003
DOIArtn 011003Doi 10.1115/1.4000636