Semisolid melt squeezing procedure for production of open-cell Al–Si foams

•Semisolid melt squeezing was employed for production of open-cell Al–Si foams.•The cell walls dendritic microstructures were improved into non-dendritic morphology.•Microstructure refinement improved the mechanical properties of final foams.

Melt squeezing process in semisolid state was used for the first time for production of open-cell Al–Si foams with improved microstructural and mechanical characteristics. First a given amount of preheated NaCl particles was stirred into molten A356 alloy. Stirring continued during solidification of the slurry until reaching a given solid fraction of primary particles. The resulting mixture was pressed by a perforated piston to squeeze a controlled amount of the residual meltout. Open-cell foams were achieved by leaching the final Al–Si–NaCl composites in water. The suitable values of the NaCl particle size, pressurizing temperature, melt to salt ratio and piston pressure for production of uniform and high integrity foams were obtained to be 3400 μm, 605 °C, 1.5:1 and 10 MPa, respectively. The results showed that the semisolid processing employed could refine and modify the microstructure of the cell ligaments in the final foams. Mechanical properties of the foams such as energy absorption and fracture toughness were also improved by the semisolid processing.