Agradecimentos: The authors would like to thank Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP—Project 2006/00935-6), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq—Project 47081-2006-6) and Fundação Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) for the financial support received, and the School of Mechanical Engineering at the University of Campinas (FEM/UNICAMP) for the infra-structure received Ver menos

The thixoformability of new Al-Si-Cu alloys was evaluated and characterized by their microstructural and rheological behavior. Alloys Al1Si2.6Cu, Al2Si2.6Cu, Al4Si2.6Cu, and Al7Si2.6Cu were produced with the addition of Al5Ti1B grain refiner alloy. The materials were heat treated under two controlled conditions: holding times of 0, 30, 90, and 210 s and solid fraction of 45 and 60%. The evaluation of the microstructure and semisolid behavior was characterized by globule size, shape factor (SF), minimum stress to flow, maximum stress, and apparent viscosity. The heat treatment times promoted the globularization of solid phase particles to achieve better apparent viscosity results for the alloys treated for 210 s. Both 45 and 60% solid fraction showed no significant differences in terms of SF, but the alloys containing lower solid fraction showed better performance for apparent viscosity. Better working ranges for these new Al-Si-Cu alloys were determined reaching average strain of 0.5 MPa and apparent viscosity of 105 Pa s Ver menos