A novel two-step processing method for fabrication of in situ Al2O3np/Al-Al11Ce3 nanocomposite

In situ Al2O3np/Al-Al11Ce3 nanocomposite was successfully synthesized from Al-CeO2 system using a novel two-step processing method that combines liquid-state mechanical mixing (step-I) and sonochemistry melt reaction (step-II). The microstructural evolution and mechanical properties were investigated by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron spectroscopy (TEM) and tensile tests, respectively. A good spatial distribution of CeO2 particles in the Al melt was achieved due to reactive wetting during step-I, and the following formation of Al2O3np during step-II was attributed to the cavitation-accelerated interfacial reaction. The solidified microstructure comprised uniformly dispersed Al2O3np in the matrix and ultrafine lamellar Al-Al11Ce3 at the grain boundaries. Such unique microstructure endowed Al2O3np/Al-Al11Ce3 nanocomposite with a good balance between tensile strength (175 MPa) and ductility (18.5%). The strengthening mechanisms of the nanocomposite included grain refinement, Orowan strengthening and quench strengthening, among which Orowan strengthening contributed the most to the yield strength of the nanocomposite.

Graphical AbstractMicrostructural characterization of the step-II specimen (SEM (inset image of eutectic structure) and TEM and SAED)Figure optionsDownload as PowerPoint slide