Evolution of microstructure and mechanical properties of [Cu–10Ni]–Si3N4 nanocomposites developed using mechanical alloying and spark plasma sintering

Abstract

This study focused on the production of [Cu–10 Ni]x–x wt% Si3N4 (x = 0, 3, 6, 9 and 12 wt%) nanocomposites through mechanical alloying followed by spark plasma sintering. An exhaustive exploration was carried out on the synthesised nanocrystalline/nanocomposite particles and sintered samples to study their structural characterisation and microstructural changes after 20 h of MA. The mechanical behaviour in terms of the compression test was carried out and correlated with the microstructural evaluations. The results indicated that the incorporation of Si3N4 nanoparticles decreased the matrix powder particle size considerably owing to the domination of fracturing mechanism. The results also showed that a higher strain hardening rate followed by the breaking up of the matrix powder particles occurred in the nanocomposite powders. The powder morphology of the nanocrystalline [Cu–10Ni] matrix ensured the uniform distribution of Si3N4 nanoparticles within it leading to the formation of dislocations in commensurate with the reinforcement addition. The sintered samples exhibited improved compression strength owing to the embedment of Si3N4 nanoparticles, strong bonding between the Si3N4 particles and the matrix, engendered dislocations and grain refinement. The ductility was examined and the strengthening mechanisms were computed for the deformed specimens. The results explained that the grain size, dislocation, and Orowan strengthening contributed more to the total strength and influenced the properties compared to other strengthening mechanisms.