AIRCRAFT ENGINEERING AND AEROSPACE TECHNOLOGY, cilt.96, sa.2, ss.185-192, 2023 (SCI-Expanded)
This study aims to investigate the fatigue crack
propagation behavior of SiC particle-reinforced 2124 Al alloy composites under
constant amplitude axial loading at a stress ratio of R = 0.1. For this
purpose, it is performed experiments and comparatively analyze the results by
producing 5, 10, 15 Vol.% SiCp-reinforced composites and unreinforced 2124 Al
alloy billets with powder metallurgy (PM) production technique. With the
PM production technique, SiCp-reinforced composite and unreinforced 2124 Al alloy
billets were produced at 5%, 10%, 15% volume ratios. After the produced billets
were extruded and 5 mm thick plates were formed, tensile and fatigue crack
propagation compact tensile (CT) samples were prepared. Optical microscope
examinations were carried out to determine the microstructural properties of
billet and samples. To determine the SiC particle–matrix interactions due to
the composite microstructure, unlike the Al alloy, which affects the crack
initiation life and crack propagation rate, detailed scanning electron
microscopy (SEM) studies have been carried out. Optical microscope examinations
for the determination of the microstructural properties of billet and samples
showed that although SiC particles were rarely clustered in the Al alloy matrix,
they were generally homogeneously dispersed. Fatigue crack propagation rates
were determined experimentally. While the highest crack initiation resistance
was achieved at 5% SiC volume ratio, the slowest crack propagation rate in the
stable crack propagation region was found in the unreinforced 2124 Al alloy. At
volume ratios greater than 5%, the number of crack initiation cycles decreases
and the propagation rate increases. As a requirement of damage tolerance
design, the fatigue crack propagation rate and fatigue behavior of materials to
be used in high-tech vehicles such as aircraft structural parts should be well
characterized. Therefore, safer use of these materials in critical structural
parts becomes widespread. In this study, besides measuring fatigue crack
propagation rates, the mechanisms causing crack acceleration or deceleration
were determined by applying detailed SEM examinations.