Experimental investigation and characterization of in situ synthesized sub micron ZrB2-ZrC particles reinforced hybrid AA6061 aluminium composite

Abstract

In the present work, AA6061 aluminum matrix composite (AMCs) was fabricated by mixing AA6061 matrix with the byproducts of in situ reaction namely ZrB2 and ZrC sub micron particles. The in situ reaction took place between K2ZrF6, KBF4 and SiC particles. The Fabrication of AMCs was done under a controlled environment using an electric stir casting furnace. The mechanical and microstructural properties of as cast AMCs were investigated by Differential thermal analysis (DTA), x-ray diffraction patterns (XRD), Field emission scanning electron microscope (FESEM), Electron back-scattered diagram (EBSD), and transmission electron microscopy (TEM). The in situ formation of ZrB2 particles in AA6061 aluminum matrix occurred at a temperature of 852.8 °C and ZrC particles at 1116.8 °C, which was confirmed by Heat flow curves obtained by differential thermal analysis (DTA). The formation of ZrB2 and ZrC particulates in the AMCs is also ascertained by XRD and FESEM results. The homogeneous distribution of in situ formed ZrB2 and ZrC particles in the AMCs with good interfacial bonding was confirmed from the FESEM micrographs. The refinement of grains of aluminum matrix by the in situ formed ZrB2 and ZrC particles was proved by EBSD maps. The in situ formed ZrB2 and ZrC particles in the AMCs exhibited hexagonal and spherical shapes, thermodynamically stable structure, increased the microhardness and UTS of in situ fabricated AMCs.