Experimental correlation between varying silicon carbide and hardness values in heat-treated Al-Si-Fe/SiC particulate composites

The effects of varying silicon carbide on the hardness values of heat-treated Al-Si-Fe/SiC particulate composites have been investigated. The 5-25% SiC additions were used for the production of different grades of Al-Si-Fe/SiC particulate composites. The composites samples were solution heat-treated at 500 °C for 3 h and quenched in warm water at 65 °C, aged at 100, 200 and 300 °C with various ageing time between 60 and 660 min at 60 min interval. Hardness measurements were made using Rockwell hardness tester. Experimental correlations obtained between the varying silicon carbide addition, heat-treatment parameters and the hardness values were analyzed using kinetic of ageing and factorial analysis (2K). The results show that hardness increases with increasing percentage of silicon carbide addition in the alloy and decreases with increasing ageing time. These results, which are in agreement with the experimental findings for these ageing time and temperatures. The increases in hardness values during ageing are attributed to formation of a coherent and uniform precipitation of the second phase in the matrix of the metal. A substantial improvement in hardness has been achieved in the reinforced metal matrices produced.