Preparation and Characterization of Iron Matrix Syntactic Foams with Glass Microspheres via Powder Metallurgy

Iron matrix syntactic foams with four different glass microsphere fractions were prepared via powder metallurgy. Effects of compaction pressure and lubricant addition on the microstructure and the mechanical properties were investigated. It was observed that matrix densification and fracture, softening, shrinkage, and bonding of the microspheres tended to increase with the compaction pressures. The compaction pressure incurring microsphere fractures was in inverse ratio to the microsphere fraction. The fracture and softened microspheres degraded onset of plateau stress values proportionally to the microsphere fractions at low compaction pressure, while enhanced and stabilized them at about 240 MPa at higher pressures regardless of the microsphere fraction, owing to increased load bearing capacity by a formation of solid particle-like microspheres. The lubricant formed pores in the matrix or accelerated densification and microsphere fractures depending on the microsphere fractions, while it had no significant effect on mechanical characteristics except brittleness.