Chromium carbide, carbon nano tubes and carbon fibers reinforced magnesium matrix hybrid composites prepared by spark plasma sintering

Abstract

This investigation presents the fabrication of hybrid Mg-Cr3C2+carbon fibers (Cf)+carbon nano tubes (CNTs) metal matrix composites through spark plasma sintering. 10 wt%Cr3C2, 1 wt% Cf and 1 wt%CNTs were added to Mg powders and mixing process was done through high energy mixer mill in ethanol media for 10 min. The sintering temperatures of 400 and 450 °C were selected at an initial and final pressure of 10 and 30 MPa, respectively to process the hybrid composite in vacuum condition of 16 Pa. Considering XRD detection limits, the XRD investigation revealed the Cr3C2 and Mg peaks as crystalline phase without any reaction products between the components. FESEM images demonstrated distribution of reinforcements at the Mg grain boundaries with some agglomerated CNTs. In the case of carbon fibers, the related microstructure of the sintered sample at 400 °C showed formation of some disjoints among the fibers, while these mentioned disjoints were eliminated by increasing sintering temperature to 450 °C. Moreover, the fracture toughness of the prepared composites showed carbon fiber tunnels, imprints and ruptures for both of the prepared samples; while the amounts of tunnels and imprints decreased with an increase in sintering temperature. The higher relative density of 99.11 ± 0.2%, bending strength of 247 ± 16 MPa and Vickers hardness of 169 ± 18 HV1 were obtained for the prepared hybrid composite at 450 °C.