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    Al-Si-Cu-Mg Matrix Composites with Graphene: PM-Based Production, Microstructural, and Mechanical Properties
    (Wiley-V C H Verlag Gmbh, 2024) Senyurt, Berk; Agaogullari, Duygu; Akcamli, Nazli
    Few-layered graphene (FLG)-reinforced Al-Si(10 wt%)-Cu(2 wt%)-Mg(1 wt%) matrix composites are prepared by the high-energy mechanical alloying (MA) method, which is a branch of powder metallurgy. Al-10Si-2Cu-1Mg matrix is reinforced with varying amounts of FLG (0, 0.5, 1, 2, and 5 wt%) via MA for different durations (0, 2, 4, and 8 h), and consolidation is conducted by pressureless sintering. Microstructural, mechanical, and tribological characterizations are applied to nonmechanically alloyed (non-MAed) and mechanically alloyed (MAed) powder and bulk composites comparatively. The bulk composites produced via the MA-containing processing route illustrate more homogeneous phase distributions and higher densification rates. The FLG/AlSiCuMg composites exhibit enhanced materials properties compared to their unreinforced counterparts. The addition of 1 and 2 wt% FLG to the Al-10Si-2Cu-1Mg alloy, respectively, improved the mechanical properties in terms of microhardness (155 and 162 HV), compression strength (441 and 412 MPa), and wear rate (11.5 x 10-4 and 9.2 x 10-4 mm3 N-1 m). Therefore, the experimental results show that graphene ensures a reinforcing effect on the Al matrix, at least provided by some of the ceramic particles. This study explores the microstructural, tribological, and mechanical properties of few-layered graphene (FLG)/Al-10Si-2Cu-1Mg composites produced by the powder metallurgy route, including a high-energy mechanical alloying (MA) stage. FLG is synthesized in-house by the arc-discharge method. The effects of MA processing duration along with various FLG amounts on the materials properties of the powder and bulk composites are investigated.image (c) 2024 WILEY-VCH GmbH
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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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    Few-layered graphene/Al-Cu alloy matrix composites: Mechanical, tribological and corrosion properties
    (Elsevier, 2024) Senyurt, Berk; Yaman, Kubra Cankaya; Akcamli, Nazli
    Nano-sized graphene incorporated Al-5.5 wt% Cu alloy matrix composites were produced via powder metallurgy. Nano-sized graphene powders obtained via the arc-discharge method were incorporated into Al and Cu powders in varying amounts (0-5 wt%) by applying a high-energy ball milling (HEBM) process for different durations. The consolidated composites were prepared by the succeeding uni-axial pre-compaction and pressureless sintering stages. The as-blended and mechanically alloyed (MAed) powders and bulk composites were comparatively characterized in terms of their physical, thermal, microstructural, tribological, mechanical, and corrosion properties depending on the graphene amount and the duration of mechanical alloying (MA). After 4 h of MA, the starting as-blended powders presented as coarse and discrete particles gained a refined and homogenized microstructure with more equiaxed dimensions. Bulk FLG/Al-5.5Cu (FLG in amounts of 0, 0.5, 1, 2, and 5 wt%) composites are ever-increasing hardness values with rising graphene as 109, 101, 128, 238, and 263 HV, respectively. The compressive strength improved gradually to 495 MPa using graphene up to 1 wt%, though contrary to the high hardness values, a drastic decline was observed by 5 wt% graphene incorporation. Besides, the wear resistance of composites outperformed that of the Al-5.5Cu matrix by incorporating this amount of reinforcement together without a deterioration in the corrosion resistance.
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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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    Powder metallurgical fabrication of graphene reinforced near-eutectic Al-Si matrix composites: Microstructural, mechanical and electrochemical characterization
    (Elsevier - Division Reed Elsevier India Pvt Ltd, 2022) Akcamli, Nazli; Senyurt, Berk; Gokce, Hasan; Agaogullari, Duygu
    Al-10 wt% Si matrix composites reinforced with a few-layered graphene (FLG) were fabricated via a powder metallurgical route. FLG in varying amounts (0.25, 0.5, 1, 2, and 5 wt%) was incorporated into the Al10Si matrix via mechanical alloying (MA) for different durations in a high-energy ball mill. The mechanically alloyed (MAed) powders were consolidated by uniaxial pressing and pressureless sintering processes. The as-blended (non-MAed) and MAed powders and bulk composites were investigated comparatively in terms of microstructural, thermal, mechanical, tribological and corrosion properties. The MAed powders demonstrated refined and semi-equiaxed particle morphology with reduced crystallite size values. Additionally, the FLG/Al10Si composites exhibited advanced microstructural and mechanical properties by the contribution of MA and reinforcing particles compared to those of the as-blended and unreinforced matrix. The highest hardness and lowest wear rate values were obtained for the 4 h-MAed Al10Si-2FLG (138 HV and 6.485x10-4 mm(3)/N.m) and Al10Si-5FLG (178 HV and 7.456x10-4 mm(3)/N.m) composites. Moreover, the compressive strength of the Al-10Si matrix improved approximately by 50 and 20% via 0.5 and 2 wt% FLG addition, respectively. Also, lower corrosion resistance properties were observed for the FLG reinforced composites compared to the Al10Si matrix. (c) 2021 Karabuk University. Publishing services by Elsevier B.V.
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    Processing and Characterization of Al-4Cu Matrix Composites Reinforced with Few Layered Graphene
    (Springer India, 2022) Kaykilarli, Cantekin; Kucukelyas, Burak; Akcamli, Nazli; Uzunsoy, Deniz; Cansever, Nurhan
    Few-layered-graphene (FLG)-reinforced Al-4 wt.% Cu matrix composites were produced via the powder metallurgy (PM). FLG was incorporated into the matrix via a mechanical alloying (MA) process conducted for 5, 7 and 9 h in a planetary ball mill. The mechanically alloyed (MA'ed) powders were consolidated by uniaxial pressing and pressureless sintering. Properties of the Al-4Cu-xFLG composites were examined via Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), Optical Microscopy (OM), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDX), Archimedes method, microhardness, compressive and wear tests. According to the mechanical characterization, FLG addition relatively improved the hardness, whereas it caused the decline of compressive strength. However, the specific wear ratio of the same sample increased by two times compared to the Al-4Cu.
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    Si3N4 reinforced Al-Si-Mg matrix composites: Powder metallurgy fabrication, PEO coating and characterization
    (Elsevier, 2025) Yurekturk, Yakup; Senyurt, Berk; Celtik, Cansu; Kucukelyas, Burak; Akcamli, Nazli
    Si3N4-reinforced Al-6.5Si-0.5Mg matrix composites were produced via a powder metallurgy (PM) method, which includes high-energy mechanical milling (HEBM) and pressureless sintering. An oxide-based ceramic protective coating was applied to the PM composites using the plasma electrolytic oxidation (PEO) technique. The novel aspect of this study lies in applying a PEO coating on particulate-reinforced AMCs produced through PM, which further enhances the composites' surface properties and corrosion resistance. The microstructural characterizations indicate that the mechanically alloyed (MA'ed) powders comprise Si and Mg phases integrated within the Al matrix along with embedded Si3N4 reinforcement particles, thus ensuring a composite structure. Hence, applying the mechanical alloying (MA) process and Si3N4 incorporation enhanced the densification and hardness properties of the Al-Si-Mg matrix, highlighting its reinforcing effect. The hardness of MA'ed and 15 wt% Si3N4incorporated composite increases to 144 HV. Also, the PEO-coated samples outperform all uncoated samples in terms of corrosion resistance. The PEO-coated Al-6.5Si-0.5Mg-15Si3N4 composite showed an approximate 89% decrease in corrosion rate compared to the uncoated Al-6.5Si-0.5Mg base alloy. Thus, the PEO-coated sample with 15 wt% Si3N4, demonstrates superior performance, with the highest polarization resistance and a balanced charge transfer resistance, making it the most effective in corrosion protection.
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    Solid-state synthesis of Cr2AlC MAX phase from mechanically activated Cr/ Al/C powder blends
    (Elsevier Science Sa, 2025) Senyurt, Berk; Agaogullari, Duygu; Akcamli, Nazli
    This study focuses on synthesizing the ternary-layered chromium aluminum carbide phase (Cr2AlC MAX) via a milling-assisted solid-state synthesis method. The elemental powders of Cr, Al, and C were processed in a twostage process following mechanical activation (MAc) and annealing. Various parameters in both stages (such as milling time, annealing temperature, and process control agent) were examined to optimize the production of a high-purity Cr2AlC MAX phase. For this purpose, the elemental powders underwent MAc through high-energy ball milling for 1, 3, and 5 h and annealing at temperatures ranging from 700 to 1500 degrees C. The formation mechanism of the Cr2AlC phase was discussed based on detailed characterizations, including differential thermal calorimetry (DSC), X-ray diffraction (XRD), and Rietveld analyses. Additionally, the morphological properties of the synthesized powders were investigated in detail via scanning and transmission electron microscopy (SEM and TEM) techniques. The initial formation of the MAX phase was observed at 700 degrees C, and it was completed with a meager amount of chromium carbide phase at higher temperatures (99.7 % Cr2AlC at 1100 degrees C) depending on the synthesis conditions. In addition, a single-phase Cr2AlC MAX without a carbide impurity was achieved with the addition of SA, which caused an increase in the annealing temperature to 1300 degrees C.