Fabrication, microstructural characterization and finite element analysis of functionally graded Al-Al2O3 disk using powder metallurgy technique

Abstract

In the present work, powder metallurgy technique was employed to fabricate a three-layer functionally graded (FG) disk. The volume fraction of metal-ceramic composition changes radially as layer-1 (100 % Al), layer-2 (95 %Al +5 % Al2O3), and layer-3 (90 %Al +10 % Al2O3). The microstructural investigation was carried out under an optical microscope and SEM (scanning electron microscopy) integrated with EDS, confirming a uniform distribution of reinforcement particles (alumina) in the matrix (aluminum). Interface microstructure indicates a successful fabrication of FGM (functionally graded material) as the transition is uniform in the graded layer without the development of any crack or void at the interface. In comparison to layer-1, the average increase in hardness values was found to be 18 % and 29 % for layer-2 and layer-3 respectively. An increment in hardness was observed in layers where alumina composition is higher. The Archimedes principle was employed to calculate the experimental density of the sample, and the theoretical models were presented to effectively estimate the density of porous FG materials. Furthermore, theoretical models for estimating material properties such as Young's modulus and yield strength of individual layers were proposed on the basis of material composition and particle shapes obtained from the microstructure of FG disk. These material properties were then used in finite element formulation for the application of rotating disk, the validation of which is also proposed. Subsequently, finite element analysis was employed to perform stress analysis on layered FG disk when subjected to centrifugal loading.