Microstructure and Nanoindentation response of Si 3 N 4 -Reinforced Magnesium-based Composite Synthesized by Powder Metallurgy Route

This paper reports the development and characterization of magnesium (AZ91D) alloy-based composites strengthened with silicon nitride (Si 3 N 4 ) particles as reinforcements through the powder metallurgy (P/M) technique. The percentage of Si 3 N 4 particles was varied from 0 to 10 weight percent in steps of 2.5 weight percentage. Ball milling was adapted to ensure uniform dispersion of Si 3 N 4 particles in magnesium alloy; the ball-milled composite powders were compacted at a pressure of 60 mpa using a hydraulic press at room temperature. The compact green specimen was sintered in a tubular furnace at a temperature of 610 °C for 4 h. Microstructure studies showed homogenous dispersion of Si 3 N 4 particles in AZ91D magnesium alloy. X-ray diffraction (XRD) pattern confirmed the presence of Si 3 N 4 particles in magnesium alloy. The measured density of the developed composites increased with an increase in Si 3 N 4 reinforcements. The addition of Si 3 N 4 particles remarkably improved the hardness of the composite. Hardness and Young’s modulus were determined by the nanoindentation technique.