This paper delivers a detailed review of the influence of material and process variables on the microstructure, mechanical and tribological characteristics of functionally graded aluminum matrix composites (FGAMCs) produced by the ex-situ centrifugal casting method from previous studies. Also, the basic principle and classification of centrifugal casting to produce FGAMCs are illustrated. The ceramic reinforcement particles are classified based upon their uses in the processing of FGAMCs through the ex-situ centrifugal casting technique. In addition, using the linear regression model, an effort has been made to optimize the material and process variables to get enhance the mechanical properties. It is seen from the optimization while mold preheating temperature ranges 250–350 °C, centrifugal speed kept between 600 and 1300 rpm, pouring temperature in the range of 740–760 °C having reinforcement particle of 10–15 wt%, with an average particle size of 18–50 µm yield the maximum of hardness and tensile strength. This paper aims to provide direction to future researchers to develop advanced material using this route and thus, to boost technological growth.

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In this paper, Inconel 718 (IN718) superalloy was processed by laser powder-bed fusion additive manufacturing (L-PBFAM), followed by heat treatment. High-resolution nanoindentation was used to investigate the complex deformation mechanisms that occurred at various length scales in both conditions. The nanoindentation elastoplastic maps show a strong crystal orientation dependency of modulus and hardness, which is attributed to the high mechanical anisotropy of IN718. The hardness map effectively resolves complex microscale strength variation imparted due to the hierarchical heat distribution associated with the thermal cycles of L-PBFAM. The disproportionately high hardening effect of Nb, Mo-rich chemical segregations and Laves phases in dendritic structures is also observed. The heat treatment resulted in a 67% increase in yield strength (from 731 MPa in the L-PBFAM condition to 1217 MPa in the heat-treated condition) due to the activation of multiple precipitation-strengthening mechanisms. The nanoindentation mapping of a heat-treated sample delineates the orientation-dependent hardness distribution, which apart from high mechanical anisotropy of the alloy, is also contributed to by a high degree of coherency strengthening of the D022 γ″-precipitates oriented parallel to the <001> crystal plane of the γ-matrix. The mean hardness of the sample increased from 13.3 GPa to 14.8 GPa after heat treatment. Evidence of extensive deformation of twin networks and dislocation cells was revealed by transmission electron microscopy of the deformed region under the nanoindentation tip.