Behavioural Characterization of Aluminium metal matrix Nanocomposites

Abstract

This thesis is focused on the fabrication of metal matrix nanocomposite through powder metallurgy technique. Results revealed the improved tensile strength hardness and lowest wear rate of M2 attributing the agglomeration cluster formation and better diffusion of nanoparticles in the matrix material as compared to all other sample conditions where porosity inhomoginity and improper bonding was observed. On revealing the SEM fractographs the failure mode of M2 sample transformed in to ductile failure mechanism. The evolution of microstructure grain boundary character and micro texture of fabricated nanocomposites was investigated through EBSD in the present research work. The fraction of high angle boundaries was observed more in combined reinforcing samples whereas a single reinforcing sample showed fewer HAGBs. Micro texture results showed the strong textures components for pure sintered Al sample P and mixed reinforcement composites whereas for single reinforcing sample showed weak textures near to transverse direction. Out of all fabricated composites M2 revealed the maximum compressive strength and least wear rate attributing formation of nanocluster causing grain boundary pinning effect. The dominant failure mechanism for all samples was also detected and found to be a mixed mode ductile failure mechanism for M2 while other sample failed through ductile as well as mixed mode mechanisms. The fracture toughness for all sample compositions estimated for longitudinal direction was accessed through apparent fracture toughness and Equivalent energy fracture toughness and J integral measurement. The result revealed the exceptionally good fracture toughness parameters of M2 as compared to the pure sintered sample. newline