Nafisi, S.Lashkari, O.Ghomashchi, R.Ajersch, F.Charette, A.2011-10-112011-10-112006Acta Materialia, 2006; 54(13):3503-35111359-64541873-2453http://hdl.handle.net/2440/66639A comprehensive study was carried out to establish the effect of melt treatment using Ti-B grain refiner and Sr modifier additions on the microstructural evolution and rheological properties of A356 aluminum alloy in the semisolid state. Rheocast billets of 75 mm in diameter and ∼140 mm in length, prepared by the SEED process, were deformed and several parameters were investigated to characterize the flow behavior of the billets in a compression test. Strain-time graphs were used to calculate the viscosity and liquid segregation was monitored to identify the optimum conditions for melt treatment. It is shown that non-treated alloy has the highest apparent viscosity. Refined semisolid billets have smaller particle size and more globularity of primary α-Al particles and as a result deform and flow more easily. It is postulated that modifier addition reduces the liquid surface tension and leads to improved deformability. © 2006 Acta Materialia Inc.enCopyright © 2006 Acta Materialia Inc.SemisolidSEED processRheological propertiesViscosityGrain refinerModifierJournal article002010860810.1016/j.actamat.2006.03.0160002398238000112-s2.0-3374586697729763Ghomashchi, R. [0000-0003-3633-2296]