LAUSR

The AA2014/5 wt. % carbonized eggshells metal matrix composite used in this study was fabricated by electromagnetic stir casting technique and immediately extruded on universal testing machine at 60 MPa using cylindrical H13 tool steel die coated with graphite to avoid upper flow of eggshells particles and to improve wettability of eggshells with AA2014 alloy. Microstructures of composites show some agglomerations in non-extruded samples while uniform distribution of carbonized eggshell particles. Optimum combination of precipitation hardening parameters achieved using response surface methodology to further improve the properties of AA2014/5 wt. % eggshell composites. Optimum values of solutionizing time, aging temperature and aging time were found to be 4.5 h, 250℃ and 13.5 h, respectively. More grain refinement of extruded AA2014/5 wt. % eggshell composites were observed after heat treatment at optimum precipitation hardening parameters. After heat treatment, fractographs of the AA2014/5 wt. % eggshells composite showed that fracture is dominated by trans-granular type. Density of the AA2014 is 5% higher than AA2014/5 wt. % eggshells metal matrix composite. It is observed that mechanical properties improve when carbonized eggshell particles are reinforced in matrix AA2014 aluminium alloy. After the heat treatment at optimum precipitation hardening parameters, mechanical properties are further improved.