Synergistic strengthening mechanism and microstructural evolution of Al-Zn-Mg-Cu/ Al2O3/Y2O3 hybrid nanocomposite via mechanical alloying and hot pressing

Abstract

Mechanical alloying (MA) and hot pressing (HP) were utilized to fabricate a hard ceramic dispersion (Y2O3 and Al2O3) in the Al-Zn-Mg-Cu alloy. Fracturing and severe plastic deformation phenomena during MA significantly reduced the powder particles to nanosize, and peak broadening was observed, along with a particle change from a flake shape to a spherical one. For the 20 h milled consolidated sample, the hybrid-reinforced composite sample exhibits higher Vickers microhardness, nanoindentation, and compressive strength compared to the blended samples at 0 h due to grain refinements and homogeneous dispersion of reinforcements. A comprehensive analysis of various strengthening mechanisms for the obtained compressive strength was quantitatively determined, and the results indicate that precipitate and dispersoid strengthening mechanisms were the principal ones compared to others (grain size, solid solution, and dislocation strengthening mechanisms). These findings mark the beginning of hybrid composite development through the MA and HP techniques.