Effect of B₄C Particles on CTE and Thermal Conductivity of Al2214/3Gr_p/xB₄C_p Hybrid Metal Matrix Composites

In this investigation, hybrid aluminium metal matrix composites containing a constant weight fraction (3 wt%) of graphite (Gr_p) with different weight fractions (1.5, 3, 4.5, and 6 wt%) of B₄C_p particles (Al/3Gr_p/xB₄C_p) were synthesized by an advanced modified liquid metallurgical technique. The Al/3Gr_p/xB₄C_p hybrid composite specimens were subjected to microstructure studies under a scanning electron microscope (SEM) integrated with an energy-dispersive X-ray spectroscope (EDX). The SEM micrographs reveal a uniform distribution of reinforced particles in the aluminium (Al) matrix phase, and elemental composition is identified by an EDX analysis. Further, the phase identification of Al/3Gr_p/xB₄C_p composite samples was performed by X-ray diffraction analysis. Experimental values of Al/3Gr_p/xB₄C_p hybrid composites showed that the thermal expansion coefficient values declined with increased wt% of B₄C_p particles and increased operating temperatures of hybrid composites. Further decreases in thermal conductivity of hybrid composites were observed with an increased wt% of B₄C_p particles. Finally, the results were compared with theoretical models.