An experimental crack propagation analysis of aluminum matrix functionally graded material

Abstract

In this study, a functionally graded cylindrical specimen was obtained via centrifugal casting and its fatigue crack behavior was investigated. Aluminum 2014 alloy and SiC were used as matrix material and ceramic particle, respectively. The distribution of SiC and the mechanical properties of material through cylinder wall thickness were varied because of the centrifugal force during centrifugal casting. Variations in microstructure and hardness were examined. A cylindrical specimen was cut through its thickness in four sections through vertical slicing. Tensile strength was tested on each section to determine the mechanical properties that can be varied such as Young's modulus, tensile strength, and yielding stress. To investigate the effect of variation in the mechanical properties and distribution of SiC particles on fatigue crack behavior, fatigue crack growth tests were applied under tensile cyclic load with stress ratio R = 0.1. The samples were prepared in three separate groups: central notched, single-edge notched on SiC-rich side, and single-edge notched on aluminum-rich side. It was found that SiC distribution affected fatigue crack initiation and propagation. The fatigue life increased up to 350% because of increasing SiC ratio for central notched specimens. Cracks were started out later on the single-edge notched SiC-rich side compared to aluminum-rich side whose fatigue life increased up to 500%. In addition, it was found that unreinforced aluminum material's fatigue life was lower than that of reinforced material.