Development of aluminium composites through P/M route:: Case of nitrides

In the present study aluminium matrix composites reinforced with differente nitredes have been fabricated and studied. Processing technique was based on a powder metallurgy route consiting of mixing of powders, cold uniaxial compaction and extrusion. Base aluminium used as matrix was the AA6061 alloy (Al-Mg-Si), together with four different reinforcements in particulate form: TiN, Si3N4, BN and Li3N. The study carried out on the composites so produced was focused on microstructural analysis and mechanical and tribological testing. Microstructure of composites presented a good distribution of reinforcements, although some banding have been observed in some samples. Porosity levels was very low, reaching a densification level close to 100%. Strength of composites were higher than the unreinforced matrix in T1 state whereas for T6 state there was not a significant increase. Advantages of composites in terms of tribological properties were only for Si3N4 because a very low friction coefficient and for Li3N for low wear rate.