Microstructural features and mechanical properties of Al 5083/SiCp metal matrix nanocomposites produced by high energy ball milling and spark plasma sintering

Al 5083 alloy powder with 10 wt.% (∼8.43 vol.%) of silicon carbide (SiCp) nanoparticulates having size of ∼20 nm were milled using a high-energy planetary ball mill to produce Al 5083/10 wt.% SiCp (Al 5083/SiCp) nanocomposite. Subsequently, the milled powders were consolidated and sintered by employing spark plasma sintering (SPS) technique in order to attain the near theoretical densification while retaining the nanostructure of Al 5083 matrix embedded with uniformly distributed SiCp. High resolution transmission microscopy (HR-TEM) analysis revealed the grain morphology and grain size of the Al 5083 matrix along with the interfacial microstructure between Al 5083 matrix and SiCp particulates. The crystallite size of ball milled Al 5083 matrix was observed to be ∼25 nm and was coarsened up to 30 nm after rapid consolidation and sintering using SPS. Compressive strength and elastic modulus of Al 5083/SiCp metal matrix nanocomposites was significantly increased to that of the un-reinforced Al 5083 alloy. Nanoindentation measurements on these nanocomposites demonstrated the hardness of ∼280 HV with an elastic modulus of 126 GPa.