Development of Functionally graded Al metal matrix layered hybrid composite reinforced with CNT, Y2O3 & SiC through PM route

In this research, we employed powder metallurgy techniques to fabricate a lightweight, high-strength hybrid reinforced aluminum metal matrix composite with 1-D graded properties. The investigation focuses on the influence of CNT, Y₂O₃, and SiC reinforcements on various aspects including structure, morphology, phase composition, thermal stability, and mechanical properties. Continuous variation of CNT and Y₂O₃ (0-2.5 wt.%) were done simultaneously to prepare a graded structure upon consolidation. Mechanical and micro structural characterizations were carried out with the aid of SEM-EDS, instrumented indentations to establish structure property co-relation. Further characterization of the composite materials was conducted using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), indentation techniques and dynamic mechanical analyser (DMA). We found that milling resulted in the uniform distribution of reinforcements and XRD analysis revealed the formation of minimum reaction products. SEM results support the intactness of interlayers in the bulk samples. Thermal properties characterized through DMA shows aboute 50% reduced coefficient of thermal expansion for the bulk FG composites.

Keywords: Mechanical Milling, Spark Plasma Sintering, Mechano-thermal processing, Powder Metallurgy, Nano Composites, Carbon Nanutubes, Cryomilling, Functionally graded Material