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In this study, authors reinforced micro (0–10 wt%)- and nano (0.8–1.8 wt%)-Al2O3 particles into the AA7075 matrix to enhance wear resistance. Comprehensive microstructural analysis, including optical microscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, confirmed the development of robust intermetallic compounds and uniform distribution of reinforcements. Using XRD analysis, peak detection of the Al2O3 and MgZn2 was observed. Al, Al2CuMg, and Al8Fe2Si were identified as the primary phases, and monolithic and composite materials both showed minor MgAl2O4 formation. Ball-on-flat tests (5 and 10 N loads) assessed wear and friction behaviors. Potentiodynamic polarization tests were employed to examine the corrosion behavior of both the monolithic alloy and the manufactured composites. The composite with 1.8 wt% nano-Al2O3 at a 5 N load demonstrated a 53% lower wear rate and 16% reduced friction. Predominant wear mechanisms included abrasive, oxidative, adhesive, and delamination. Corrosion test findings indicated that the composite containing (0.8 wt% nano-alumina and 5 wt% micro-alumina) exhibited superior corrosion resistance compared to the monolithic alloy and other composites. [ABSTRACT FROM AUTHOR]

The present study focuses on the investigation of mechanical, thermal, and corrosion behaviors of cast hybrid nano-metal matrix composites of AA7075 with Al2O3 and coconut shell ash (CSA) nano- and micro-sized particulates, respectively, as reinforcements. Using an ultrasonic assisted stir-casting technique, the hybrid composites were fabricated using 2, 4, and 6% by weight of CSA and 0.5% by weight of Al2O3 in equal proportions. SEM, EDS, XRD, porosity, tensile, damping, dislocation density, coefficient of thermal expansion, and polarization tests were used to characterize four different combinations. The findings indicated that the nano- and micro-sized particulates were spread evenly in the matrix. The dislocation density, which is caused by a thermal mismatch between the matrix and the reinforced particles, as well as composite porosity, have been found to have a significant impact on the damping behaviors of hybrid composites. Also, the thermal expansion coefficient of HMMCs decreased with the addition of Al2O3 and CSA. The corrosion resistance was gradually increased by increasing the weight percentage of reinforcement in the AA7075 matrix. [ABSTRACT FROM AUTHOR]

The present work is focused on the influences of reinforced particles on mechanical, microstructural, and tribological performances of AA7075 hybrid metal–matrix composites (HMMCs). Al2O3 and coconut shell ash (CSA) were reinforced using two-stage stir casting by varying the wt% (0–5) of reinforcement. Microstructural analysis and various phase identifications were examined with the help of scanning electron microscope (SEM) equipped with EDX and optical microscope. Various mechanical testing such as tensile, hardness, 3-point bend test, and tribological behaviors were carried out to know the HMMCs properties. Microstructural images revealed a homogeneous distribution of reinforced particles in the metal–matrix and EDX confirmed the presence of dispersed reinforcements (Al2O3 and CSA) in the HMMCs. It was seen that mechanical properties and tribological behavior have been increased after addition of Al2O3 and CSA reinforced particles whereas slightly decreased in impact strength. Transgranular cleavage facets, micro-void coalescence, dimples, and crack were shown in SEM images of fractured specimens during impact and tensile testing. [ABSTRACT FROM AUTHOR]