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Abstract Al-Si-Zn-Mg quaternary alloys represent a potential range of feedstock's for semisolid processing (SSM) that combine the advantages of the thixoforming process with the possibility of heat treatment to improve mechanical performance. In this work, the suitability of the Al-5wt%Si-5wt%Zn-0.5wt%Mg alloy for use in thixoforming was assessed by thermodynamic characterization and by an analysis of its microstructural evolution and rheological behavior. Thermodynamic analysis was performed by numerical simulation and by application of the differentiation method to Differential Scanning Calorimetry (DSC) curves for heating cycles up to 700 °C at 5 and 25 °C/min. Microstructural evolution during partial melting at 594 °C for 0, 30, 60 and 90 s and the corresponding rheological behavior were analyzed. The findings indicate good agreement between the thermodynamic behavior predicted by DSC and Calculation of Phase Diagrams (CALPHAD) and the data obtained from semisolid forging. Although the alloy has a coarse microstructure (GSmax = 200 μm), its rheological behavior is appropriate for thixoforming (σmax = 1.06 MPa and μmax = 1.79x104 Pa.s), indicating that the microstructure only plays a secondary role in determining viscosity when enough liquid (fl = 0.63) is present in the slurry to enhance the flow. The alloy is suitable for use as raw material for semisolid processing.

• Chitosan (C) was used to partially replace starch (S) in self-sustaining hydrogels. • Creep-recovery data was modeled using an approach based on the simulated annealing. • S/C hydrogel containing the lowest C replacement showed the greatest elasticity. • S/C hydrogels containing the yellow sunset (INS 110) were covered with aqueous media. • S/C hydrogel with the lowest C replacement presented the lowest INS 110 release. Biopolymers mixtures appear as a strategy to improve sensorial/technological characteristics of gel-like products. Thus, self-sustaining starch (S100/C0) hydrogels were prepared with a partial replacement of the gelling agent by 5.0 % (S95/C5), 7.5 % (S92.5/C7.5), or 10.0 % chitosan (S90/C10), and containing yellow sunset (INS 110). Major visual changes or significant differences on L * a * b * parameters were not observed for starch/chitosan hydrogels. Creep-recovery data was modeled using the simulated annealing algorithm, and relative recovery results showed an increase for S95/C5 (82.6 %), when compared to S100/C0 (72.9 %). After 312 h, chitosan strongly reduced the INS 110 release from hydrogels to an ethanolic solution (3.1∙10−4 and 4.1∙10-3 g/100 mL for S95/C5 and S100/C0, respectively) or to a sucrose solution (1.1∙10-3 and 6.5∙10-3 g/100 mL for S95/C5 and S100/C0, respectively). Such results highlighted that chitosan not only presented a techno-functionality on starch hydrogels by improving their elasticity but also by hindering the release of yellow sunset. [ABSTRACT FROM AUTHOR]