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    Characterization of the Microstructure and Mechanical Properties of a Novel Functionally Graded Material Based on Al-Zn-Cu-Mg Alloy Matrix Reinforced with Few-Layered Graphene
    (Wiley-V C H Verlag Gmbh, 2025) Borand, Gokce; Uzunsoy, Deniz
    Composite materials satisfactorily suit the needs of industrial applications. However, with the advancement of modern technology, functionally graded materials (FGMs) are becoming increasingly important in order to meet evolving customer demands. The reinforcement material in FGMs varies in quantity and arrangement across different regions, resulting in continuously changing properties and a non-uniform microstructure. Various industries widely employ aluminum (Al) alloys due to their favorable features, which include excellent stiffness, ductility, a high strength to weight ratio, and corrosion resistance. The current study facilitates the powder metallurgy (P/M) production of a novel generation of a six-layer Al-Zn-Cu-Mg alloy material graded according to increasing few-layered graphene (FLG) reinforcement. The increase in the FLG content between the layers, from the first to the last layer, results in an increase in the hardness value (HV) of the FGM by approximate to 39.13%. The most effective strengthening mechanism for FGM is grain size reduction, which is a result of the FLG content present in each layer. Moreover, the load transfer and reinforcing effect of graphene are enhanced by the strong interface bond that occurs between FLG and the matrix.
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    Fabrication of functionally graded few-layered graphene reinforced Al-4.5Cu alloy by powder metallurgy
    (Elsevier Science Sa, 2022) Borand, Gokce; Uzunsoy, Deniz
    Functionally graded materials (FGMs) are a class of innovative materials designed for needs that conven-tional composite materials cannot provide. Potential application areas such as aerospace, automobile, biomedical, defence, electrical/electronics, energy have begun to increase for the use of FGMs. Aluminium and aluminium alloys are preferred in these potential application areas for their physical and mechanical properties such as lightweight, high specific strength, high specific modulus and low thermal expansion coefficient. Graphene, one of the allotropes of carbon, is of great interest worldwide due to its superior mechanical, electrical and thermal properties. In this study, functionally graded graphene reinforced Al-4.5Cu alloy was produced by powder metallurgy. Few-layered graphene (FLG) with high purity, which was synthesized by the electric arc discharge (EAD) was reinforced to the Al-4.5Cu alloy powders that were produced by mechanical alloying as 0,0.1,0.2,0.3,0.5 and 0.7 wt%. These FLG reinforced Al-4.5Cu alloy composite powders considering FGM design with six layers, were pressed by stacking according to their various FLG contents and subjected to sintering at 570 degrees C and 590 degrees C for 3 h. It was observed that the FLG, which was graded according to their contents acting as a barrier between grains, was homogeneously dispersed in the Al-4.5Cu alloy matrix in optical and scanning electron images. According to the design of each FGM, an increase in the hardness by 37.11 % and 24.71 % was observed in the last layer compared to the first layer for sintering at 570 degrees C and 590 degrees C, respectively. (c) 2022 Elsevier B.V. All rights reserved.
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    Few-layered graphene reinforced Al-10 wt% Si-2 wt% Cu matrix composites
    (Elsevier, 2022) Senyurt, Berk; Kucukelyas, Burak; Bellek, Mustafa; Kavak, Sina; Borand, Gokce; Uzunsoy, Deniz; Akcamli, Nazli
    Few-layered graphene (FLG) reinforced Al-10 wt% Si-2 wt% Cu (Al10Si2Cu) matrix com-posites were fabricated via a powder metallurgical route. FLG powders were produced in an originally designed DC arc reactor via arc discharge method. Al, Si, Cu and FLG powders were subjected to high-energy ball milling at different durations to produce ternary Al alloy with homogeneously dispersed FLG, and bulk composites were fabricated via subsequent uni-axial compaction and pressureless sintering. The effects of varying FLG amounts and milling duration on the properties of the powder and bulk samples were investigated. The characterization of as-blended and mechanically alloyed (MAed) powders and their sin-tered forms were performed in terms of microstructural, thermal, mechanical, wear and corrosion properties. According to the results, the hardness values of the 4 h MAed Al10Si2Cu-xFLG composites were determined as 102, 154, 191 and 241 HV for x 1/4 0, 1, 2 and 5 wt%, respectively. Despite the greater hardness value of the Al10Si2Cu-5FLG-4h com-posite, its compressive strength was low due to its brittle structure. The highest compressive strength was shown by the Al10Si2Cu-1FLG as 463 MPa by an approximate increase of 53% compared to that of the Al10Si2Cu matrix. Moreover, the tribology tests showed that FLG addition (up to 2 wt%) improved the wear rate of the Al10Si2Cu matrix. However, a deteriorative effect of FLG on the corrosion resistance of the composites was determined.(c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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    Investigation of the structural properties and corrosion behavior of few-layered graphene reinforced Al-Zn matrix P/M composites
    (Elsevier, 2025) Borand, Gokce; Senyurt, Berk; Agaogullari, Duygu; Uzunsoy, Deniz; Akcamli, Nazli
    A powder metallurgical production route was employed to produce Al-7.5 wt% Zn matrix composites reinforced with few-layered graphene (FLG). The in-house synthesized FLG by the electric arc discharge (EAD) method was incorporated into the Al-7.5Zn matrix through mechanical alloying (MA) in varying amounts (0, 0.5, 1.0, and 2.0 wt%). The mechanically alloyed (MAed) powders were consolidated by uniaxial pressing, and they were subjected to pressureless sintering at 635 degrees C for 2 h. The effects of FLG contents (0, 0.5, 1, and 2 wt%) and MA duration (0, 2, 4, and 8 h) were investigated regarding the microstructural, mechanical, tribological, and corrosion properties of bulk composites. The hardness values of 4 h MAed FLG/Al-7.5Zn composites having graphene in amounts of 0, 0.5, 1, and 2 wt% were determined as 77, 89, 107, and 119 HV, respectively. Compared to Al-7.5Zn alloy, 2 wt% FLG addition significantly increased the hardness of 4 h MAed Al-7.5Zn composites by approximately 54 %. In line with the hardness results, the addition of FLG notably and gradually enhanced the wear resistance of the composites. The Al-7.5Zn matrix displayed an ultimate compressive strength (sigma ucs) of 180 MPa, which significantly rose to 287 MPa for the Al-7.5Zn-1FLG composite, indicating a 1.6-times enhancement. Moreover, the addition of this amount of graphene did not degrade the corrosion performance of the Al-Zn matrix; in fact, it resulted in a slight improvement in the corrosion resistance of the composites.
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    PROCESSING AND CHARACTERISATION OF FUNCTIONALLY GRADED MATERIALS BASED ON FEW-LAYERED GRAPHENE REINFORCED ALUMINUM
    (Tanger Ltd, 2022) Ozturk, Ozberk; Borand, Gokce; Uzunsoy, Deniz
    Functionally graded materials (FGMs) are advanced engineering materials developed due to their superior properties where traditional composite materials are not sufficient. Nowadays, the development and application of these materials for the potential areas have attracted much more attention. Aluminum (Al) is preferred for physical and mechanical properties such as lightweight, high specific strength, high specific modulus, and low thermal expansion coefficient in these potential applications. Graphene attracts great attention worldwide due to its superior mechanical, electrical and thermal properties. In the current study, few-layered graphene (FLG) produced with high purity electric arc discharge method were used to reinforce the Al matrix using various (in wt%) of 0, 0.1, 0.2, 0.3, 0.5, and 0.7 FLG by mechanically alloying (MA). Composite powders were consolidated by cold pressing with a layer by layer under 450 MPa. Al-FGM composites were designed including six layers and they were subjected to sintering at approximately 590 degrees C under argon atmosphere. The microstructure of Al-FGM was investigated by optical microscopy and scanning electron microscopy (SEM). It was observed that the FLG placed between the grains and acts as a barrier through the gradation improving the mechanical properties of the Al-FGM. Hardness value of the layer with the highest graphene content was measured as 113 HV. An increase in the Vickers hardness by 18 % was observed in the last layer with FLG content of 0.7 wt% compared to the first layer.
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    PRODUCTION OF Al-5Cu ALLOY COMPOSITES REINFORCED WITH FEW-LAYERED GRAPHENE BY POWDER METALLURGY METHOD
    (Tanger Ltd, 2022) Borand, Gokce; Ozturk, Ozberk; Aydin, Hursit Sefa; Uzunsoy, Deniz
    Aluminum based alloys have been widely used in the automotive, aircraft and defense applications because of good thermal and electrical conductivity, high tensile strength-to-weight ratio, high hardness, and ductility properties. Graphene, is an allotrope of carbon, attracts great attention worldwide due to its sp2-hybridized two-dimensional honeycomb structure, low weight, thermal, electrical, and mechanical properties. In the present study, high purity few- layered graphene (FLG) which was synthesized via electric arc discharge method (EAD) were reinforced to the Al-5Cu alloy matrix using various weight fraction of 0, 0.1, 0.3, and 0.5, by mechanically alloying (MA). These nano-composite powders were consolidated by cold pressing under 450 MPa and they were subjected to sintering at 570 degrees C and 580 degrees C for 3 hours under argon atmosphere. The microstructure of composites materials was studied by optical microscope and scanning electron microscopy. The FLG was observed to be dispersed homogeneously in the Al-5Cu alloy matrix. An increase in the micro hardness for Al- 5Cu alloy with 0.5 wt% FLG (123 HV) by 45 % was observed compared to pure Al-5Cu alloy (85 HV) sintered at 570 degrees C. Moreover, wear properties of these composite materials were investigated by means and analysis of variance (ANOVA).