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Applicability of different powder and polymer recipes in a new design powder injection molding system
(Walter De Gruyter Gmbh, 2021) Cicek, Bunyamin; Sun, Yavuz; Turen, Yunus; Ahlatci, Hayrettin
Production methods are changing day by day with the developing technology. Based on this idea, a new production logic and machine have been developed owing to polymer-supported powder injection molding (PIM). The ability of this newly designed machine (newPIM) to mold metal or ceramic powders supported by polymer binders is discussed in this study. By taking advantage of the polymer properties such as fluidity and sticking, powders are molded with a specially developed machine with high gas pressure in certain sizes. In this study, in which many parameters are processed from feedstock (FS) production to molding; metals Mg/316L and ceramics SiC/SiO2 powders have been used in different powder sizes and structures. In the newPIM process, polymers were included in four different recipes. Paraffin wax (PW), polyethylene glycol (PEG), polypropylene (PP), ethylene-vinyl acetate (EVA), poly-methyl methacrylate (PMMA) and low-density polyethylene (LDPE) have been employed in the FS with different combinations. From FS production to the molding stage; pressure, microstructure examination, weight loss, and density change features were investigated. The result indicated that the best FS and molding was obtained by the PEG+PMMA polymer composition formed with a spherical powder with a diameter below 40 mu m. The compression force of the FS in this composition was observed at approximately 3.4k N values.
Bio-properties of Mg-RE alloys: an applied study on cytotoxicity and genotoxicity
(Taylor & Francis Ltd, 2024) Djebari, Kenza; Turen, Yunus; Elen, Levent; Ahlatci, Hayrettin; Bozer, Busra Moran; Cicek, Bunyamin
This study presents a comprehensive review of magnesium alloys with rare elements. It discusses Mg-RE alloys and includes an experimental process. Thus, the data obtained by examining Mg-RE alloys provided a better interpretation of the experimental study. In this study's investigation report, Mg-RE alloys were thoroughly analyzed. In the experimental part, the cytotoxic and genotoxic results of the rare elements added to the Mg-Zn-RE master alloy are discussed. Experiments were carried out by adding Nd and Ce to this master alloy in inverse proportions. In cytotoxic data, it was observed that the viability rate in bacteria increased by up to 200%. In addition, significant genotoxic results of Mg-RE alloys were obtained, which are uncommon in the literature. As a result, a new perspective on Mg-RE alloys has been created. Cette & eacute;tude pr & eacute;sente un examen complet des alliages de magn & eacute;sium contenant des & eacute;l & eacute;ments rares. Elle discute des alliages Mg-ER et comprend un proc & eacute;d & eacute; exp & eacute;rimental. Ainsi, les donn & eacute;es obtenues en examinant les alliages Mg-ER ont fourni une meilleure interpr & eacute;tation de l'& eacute;tude exp & eacute;rimentale. Dans le rapport d'investigation de cette & eacute;tude, on a analys & eacute; & agrave; fond les alliages Mg-ER. Dans la partie exp & eacute;rimentale, on discute des r & eacute;sultats cytotoxiques et g & eacute;notoxiques des & eacute;l & eacute;ments rares ajout & eacute;s & agrave; l'alliage m & egrave;re Mg-Zn-ER. On a r & eacute;alis & eacute; des exp & eacute;riences en ajoutant du Nd et du Ce & agrave; cet alliage m & egrave;re en proportions inverses. Dans les donn & eacute;es cytotoxiques, on a observ & eacute; que le taux de viabilit & eacute; des bact & eacute;ries a augment & eacute; jusqu'& agrave; 200%. De plus, on a obtenu des r & eacute;sultats g & eacute;notoxiques significatifs des alliages Mg-ER, qui sont peu communs dans la litt & eacute;rature. Par cons & eacute;quent, on a cr & eacute;& eacute; une nouvelle perspective sur les alliages Mg-ER.
Ca and Ce Effect on the Corrosion Resistance of Hot-Rolled AZ31 Mg Alloys
(Eos Assoc, 2020) Kara, Ismail Hakki; Yousef, Taher Ali Issa; Ahlatci, Hayrettin; Turen, Yunus
In this study, AZ31 Mg alloys with added Ca and Ce were produced by low pressure die casting and were rolled at 400 degrees C. The corrosion properties of the materials were determined by immersion test for 72 hours at a 3.5% NaCl solution. The microstructure of the samples was investigated by light optical microscopy (LOM) and scanning electron microscopy (SEM) before the corrosion test. Twins, dynamic recrystallization (DRX), and the alloying elements have an important role in imparting the final corrosion resistance of the investigated materials.
Characterization and corrosion behavior of composites reinforced with ZK60, AlN, and SiC particles
(Elsevier - Division Reed Elsevier India Pvt Ltd, 2023) Sager, Abdulmuaen; Esen, Ismail; Ahlatci, Hayrettin; Turen, Yunus
In this paper, microstructure, mechanical, immersion and potentiodynamic corrosion behaviours of extruded ZK60 matrix composites reinforced with forty-five lm 15% silicon carbide (SiC) particles and aluminium nitride nanoparticle (AIN) (0.2-0.5% 760 nm) were investigated. The SiC and AlN mixtures, which are the reinforcing elements of the composites, were first mixed with magnesium powder as the main alloy, then pressed under a pressure of 450 MPa and sintered at 420 degrees C. Second, the sintered compacts are placed in the ZK60 alloy matrix at the semi-solid melting temperature, and the melt is mixed mechanically. After the melts are mixed for 30 min and a homogeneous mixture is obtained, the mixtures are poured into metal moulds and composite samples are produced. After homogenization for 24 h at 400 degrees C, the composite samples were extruded at 300 degrees C with an extrusion ratio of 16:1 and a piston speed of 0.3 mm/s. Then, microstructure characterization of all composite samples was performed and potentiodynamic and immersion corrosion behaviours were analyzed in 3.5% NaCl solution. It was seen that the corrosion resistance increased depending on the percentages of SiC and AlN reinforcement elements in the matrix. As a result, it was seen that the potentiodynamic corrosion resistance of rein-forced ZK60 + 15% SiC (ZK60SiC15), ZK60 + 15% SiC + 02AIN (ZK60SiC15AlN0.2) and ZK60 + 15% SiC + 0.5% AIN (ZK60SiC15AlN0.5) compounds increased by 1.6, 1.8 and 3.5 times compared to the unre-inforced ZK60 alloy. The immersion corrosion rates were calculated as 2090.73, 1748.19, 1479.84 and 1397.79 (mg/year) for the unreinforced ZK60, ZK60SiC15, ZK60SiC15AlN0.2 and ZK60SiC15AlN0.5 rein-forcements, respectively. As a result of the SEM and elemental spectrum response analysis of the corro-sion surfaces, the presence of a layer rich in Si-O elements on the surface of the AlN + SiC reinforced composites enhanced corrosion resistance. Additionally, the formation of the Mg2Si intermetallics in the structure of the SiC reinforced composites improved corrosion resistance, according to the XRD results.(c) 2023 Karabuk University. Publishing services 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/).
A Comparative Study on Microstructure, Mechanical and Tribological Properties of A4, AE41, AS41 and AJ41 Magnesium Alloys
(Springer, 2019) Zengin, Huseyin; Turen, Yunus; Elen, Levent
Microstructure, tensile and wear properties of as-cast A4 (Mg-4Al), AE41 (Mg-4Al-0.5Ce-0.5La), AS41 (Mg-4Al-1Si) and AJ41 (Mg-4Al-1Sr) alloys were investigated, and the results were compared with each other in this study. Microstructures were investigated by XRD, optical and scanning electron microscopes. Tensile tests were conducted at both room and elevated temperatures. Tribological properties were examined by pin-on-disk wear tests under different applied loads. Microstructure characterizations revealed that the volume fraction of second phases considerably increased by alloying additions of 1 wt.% Ce/La, Si and Sr. The microstructure of A4 alloy consisted of alpha-Mg grains and divorced beta-Mg17Al12 phases. After individual alloying additions of 1 wt.% Ce/La, Si and Sr, the secondary phases were primarily replaced by needle-shaped and massive blocky-shaped Al-11(Ce,La)(3) phases in AE41 alloy, Chinese-script-type Mg2Si phases in AS41 alloy and divorced globular-like and massive blocky-shaped Al4Sr and (Mg,Al)(17)Sr-2 phases in AJ41 alloy. The tensile tests showed that at both room and elevated temperatures alloying additions of 1 wt.% Ce/La, Si and Sr resulted in an increase in the strength but a decrease in the ductility. Among the studied alloys, AS41 alloy exhibited the best strength. Wear test results showed that AE41 and AJ41 alloys similarly exhibited the best wear resistance owing to the presence of hard and dense intermetallics. Abrasion was the main wear mechanism under low applied loads while delamination, adhesion and oxidation mechanisms were majorly observed under high applied loads.
The Cytotoxic and Genotoxic Assays of Mg-Ag Alloy Doped with Zn, Ca, and Nd Elements
(Springer, 2023) Elen, Levent; Turen, Yunus; Cicek, Bunyamin; Bozer, Busra Moren; Saud, A. Najah; Koc, Erkan
Magnesium alloys are being studied for their potential as biodegradable metals, and there is a growing need for multipurpose materials, such as those with more than one use. Binary Mg-Ag alloys were developed as implant materials, combining the beneficial qualities of magnesium with silver's well-known compatibility feature. The result shows that as the amount of the added Ag in the cast alloys increased, the secondary phases (Mg4Ag and Mg54Ag17) that appeared in the structure became more pronounced, and the grains became finer. The best percentage of Ag was found to be 3%, so Ca, Zn and Nd were added, and a study of the biocompatible Mg-3Ag alloy's cytotoxicity and genotoxicity showed that the alloy is safe for cells. In conclusion, 1/1 (total material concentration) cell viability for QE-30, QZ-30, QX-30, and QZEX3000 was 79.39 +/- 1.85, 106.46 +/- 1.99, 93.55 +/- 2.4, and 141.76 +/- 2.71%, respectively. Reducing material concentration by 50% (application at 1/2 concentration) raised viability to 96.83 +/- 1.35, 108.40 +/- 1.92, 124.71 +/- 2.76, and 129.05 +/- 3.5%, indicating the as-cast Mg + 3%Ag + 0.5% Nd-Ca-Zn alloy was extremely biocompatible.
Dry Wear Behaviour of the New ZK60/AlN/SiC Particle Reinforced Composites
(Mdpi, 2022) Sager, Abdulmuaen; Esen, Ismail; Ahlatci, Hayrettin; Turen, Yunus
This study deals with the microstructure, mechanical, and wear properties of the extruded ZK60 matrix composites strengthened with 45 mu m, 15% silicon carbide particle (SiC) and 760 nm, 0.2-0.5% aluminium nitride (AlN) nanoparticle reinforcements. First, the reinforcement elements of the composites, SiC and AlN mixtures were prepared in master-magnesium powder, and compacts were formed under 450 MPa pressure and then sintered. Second, the compacted reinforcing elements were placed into the ZK60 alloy matrix at the semi-solid melt temperature, and the melt was mixed by mechanical mixing. After the melts were mixed for 30 min and a homogeneous mixture was formed, the mixtures were poured into metal moulds and composite samples were obtained. After being homogenized for 24 h at 400 degrees C, the alloys were extruded with a 16:1 deformation ratio at 310 degrees C and a ram speed of 0.3 mm/s to create final composite samples. After microstructure characterization and hardness analysis, the dry friction behavior of all composite samples was investigated. Depending on the percentage ratios of SIC and AlN reinforcement elements in the matrix, it was seen that the compressive strength and hardness of the composites increased, and the friction coefficient decreased. While the wear rate of the unreinforced ZK60 alloy was 3.89 x 10(-5) g/m, this value decreased by 26.2 percent to 2.87 x 10(-5) g/m in the 0.5% AlN + 15% SiC reinforced ZK 60 alloy.
Effect of carbon content and drawing strain on the fatigue behavior of tire cord filaments
(Elsevier - Division Reed Elsevier India Pvt Ltd, 2018) Koymatcik, Huseyin; Ahlatci, Hayrettin; Sun, Yavuz; Turen, Yunus
In this work we aim to investigate fatigue strengths of the steel filaments in diameter of 0.25 mm with three different Carbon (0.70%C, 0.80%C and 0.90%C) and with four different drawing strains (3.25, 3.37, 3.71 and 3.76) by the pure bending test method. All fatigue tests have been carried out at room temperature and at a frequency of 10 Hz via a custom manufactured pure bending testing machine of which the fully reserved strain value, R = epsilon(min)/epsilon(max), is -1. The applied value of cyclic deformation, epsilon, has been chosen from the range 0.20%-1.07% as bending strain. The plots of S-N (Strain-Cycle) curves are based on high cycle fatigue (HCF) life is greater than or equal to 10(4) cycles. The fatigue deformation limit values have been determined as 0.55% units and 0.20% units for the steels of the 0.25NT-70C and 0.25UT-90C quality, respectively. The increase in hardness resulting from the microstructural thinning (due to drawing strain) increases the fatigue deformation limit of the steels containing 0.80%C. Despite the increase in the drawing strain, carbon content and hardness, the fatigue deformation limit decreased with increasing inclusion content. Fractured surfaces of the samples, which have been broken at both high fatigue life and fatigue deformation limit values, are inspected via SEM. The SEM inspection has demonstrated that the fatigue fracturing of the steel filaments are similar to that of baseball bat cracking. (C) 2018 Karabuk University. Publishing services by Elsevier B.V.
The effect of GNP addition on mechanical and residual stress properties of 2024-T3 aluminum and carbon fiber reinforced FML
(Iop Publishing Ltd, 2019) Askin, Mustafa Yunus; Turen, Yunus
In this study, fiber metal laminated (FML) composites were produced according to the order of 3/2 stacking by using 0.8 mm thickness 2024 T3 quality aluminum sheets, unidirectional carbon fiber fabric and epoxy resin. In the first production epoxy resin was used without additive. In the second production, graphene nano powder was added to the epoxy resin at a rate of 1%. As a result of the experiments, it was found that addition of graphene nano powder to the epoxy resin provided an increase of 9% in tensile strength and an increase of 24% in the interlaminar shear strength. The amount of permanent compressive stress in the composite increased by about 50%.
The effect of GNPs on wear and corrosion behaviors of pure magnesium
(Elsevier Science Sa, 2017) Turan, Muhammet Emre; Sun, Yavuz; Akgul, Yasin; Turen, Yunus; Ahlatci, Hayrettin
This study aims to investigate the role of graphene on wear and corrosion behaviors of pure magnesium. Magnesium/Graphene Nanoparticle (GNP) composites were fabricated via semi powder metallurgy method with a different content of graphene (0.1, 0.25 and 0.5 wt%). The effect of graphene in pure magnesium was examined by hardness, wear and corrosion tests. Microstructural and phase analysis were carried out by Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD) analysis. Experimental results revealed that, hardness values increased with the addition of graphene. There was a same trend in wear behaviors with increase of graphene rate. The best wear performance was belonging to the 0.50 wt% graphene/mg composite under load of 10N. So improvement of wear properties was achieved using graphene as reinforcement. According to the microstructural evolution, the uniform distribution was achieved for all samples but partially agglomeration could be seen in Mg-0.50 wt% graphene. Compared to the pure magnesium, corrosion performance was affected negatively in graphene reinforced composites. (C) 2017 Elsevier B.V. All rights reserved.
EFFECT OF INDIUM ADDITION ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF AS-CAST AND HOT-ROLLED AM60 MAGNESIUM ALLOY
(Tanger Ltd, 2017) Zengin, Huseyin; Turen, Yunus; Ahlatci, Hayrettin; Sun, Yavuz
In this study, effect of indium (In) addition on microstructure and mechanical properties of AM60 magnesium alloys was investigated. In additions were made by 0.2, 0.5 and 1 wt.%. Alloys were produced by conventional gravity casting in a steel mould. A homogenization treatment at 350 degrees C for 24 h was performed after casting processes. Homogenized samples were 1 pass hot-rolled by 40 % thickness reduction at 350 degrees C. The results showed that the average grain size of as-cast and hot-rolled AM60 alloys decreased with In addition. SEM analysis revealed that In addition led to formation of tiny Mg-In binary second phases at triple junctions. Tensile strength of as-cast AM60 alloy increased with increasing amount of In up to 0.5 wt.% above which it decreased. However, after hot-rolling process, AM60 alloy containing 0.2 wt.% In showed the best tensile properties. These improvements were attributed to the refinement of microstructure and dispersion strengthening by Mg In intermetallic phases.
Effect of La content and extrusion temperature on microstructure, texture and mechanical properties of Mg-Zn-Zr magnesium alloy
(Elsevier Science Sa, 2018) Zengin, Huseyin; Turen, Yunus
The microstructure, texture and mechanical properties of Mg-6wt%Zn-0.5 wt%Zr (ZK60) alloys with different La contents (0, 0.5 and 1 wt%) were investigated. The alloys were produced by low-pressure die casting and extruded at 300 degrees C and 400 degrees C, following homogenization at 400 degrees C for 24 h. La addition to ZK60 alloy resulted in a formation of Mg-Zn-La ternary phase, generating a semi-continuous network structure in their as-cast state. After extrusion, secondary phases were broken into fine particles distributed along the extrusion direction. These fragmented particles led to a nucleation of new grains around them i.e. particle stimulated nucleation (PSN), and promoted dynamic recrystallization (DRX) during extrusion. Therefore, increasing La content led to an increase in DRX fraction. Higher extrusion temperature resulted in larger DRXed grains and higher DRX fraction. The basal texture intensity was also decreased with increasing La addition and extrusion temperature by PSN mechanism and solute atoms of La. The ZK60-1La alloy extruded at 300 degrees C showed a superior yield strength of 311 MPa and ultimate tensile strength of 360 MPa as a result of significant grain refinement and dispersion strengthening. Increasing extrusion temperature resulted in a decrease in yield and ultimate tensile strengths and increase in ductility. (C) 2018 Elsevier B.V. All rights reserved.
Effect of Rolling Deformation on Microstructure and Mechanical Properties of As-Cast and Rolled ZM21 Magnesium Alloy
(Springer, 2023) Ozdemir, Umit; Koc, Erkan; Turen, Yunus; Elen, Levent; Cicek, Bunyamin; Saud, A. Najah
The current study aimed to improve the microstructure and mechanical properties of ZM21 magnesium alloy by using the rolling thermomechanical process at various temperatures (275 and 375 degrees C) and rates (40 and 60%). The rolled samples' grain size was examined, and it was found that the grain size decreased by 40% during hot deformation, reaching a grain size of 15.91 mu m. Surface roughness values were examined and found to be the lowest (parallel and perpendicular to the rolling direction) at a 60% rolling rate in 275 degrees C and the highest 40% at 375 degrees C. The highest tensile strength was obtained at a rolling rate of 60% at 375 degrees C, but it showed brittle fracture during testing. Accordingly, while the 275 degrees C rolled samples showed ductile fracture behavior, a slight reduction in mechanical properties was observed when the rolling ratio was set at 60%.
Effect of Sn addition on microstructure, mechanical and casting properties of AZ91 alloy
(Elsevier Sci Ltd, 2013) Turen, Yunus
In this study, effect of Sn addition on microstructure, mechanical and the casting properties of AZ91 magnesium alloy have been studied. Results from the microstructural analysis showed that refinement of Mg17Al12 phase took place and new Mg2Sn phase was formed as Sn was added into the AZ91 alloy. Fluidity increased with 0.5 wt.% Sn content then decreases rapidly as the Sn content exceeded above 0.5 wt.%. Hot tear susceptibility (HTS) decreased with 0.5 wt.% Sn addition to AZ91 magnesium alloy above which it increased considerably. Tensile strength and elongation increased by addition of up to 0.5 wt.% Sn above which it decreased with increasing Sn content. The increase of mechanical properties was attributed to transformation of lamellar to fully divorced eutectic beta phases by 0.5 wt.% Sn addition existed in grain boundaries of the magnesium matrix. The reduction in the mechanical properties above 0.5 wt.% Sn was attributed to formation of clustered Mg2Sn phase. (C) 2013 Elsevier Ltd. All rights reserved.
Effect of Y addition on microstructure and corrosion behavior of extruded Mg-Zn-Nd-Zr alloy
(Keai Publishing Ltd, 2020) Zengin, Huseyin; Turen, Yunus
In this study, the effect of Y addition (0, 0.5, 1 and 2 wt%) on microstructure and corrosion properties of Mg-6Zn-0.5Zr-1Nd (wt%) alloy was investigated. The alloys were produced by low-pressure die casting method and extruded at 300 degrees C and 400 degrees C after homogenization treatment at 400 degrees C for 24 h. The results showed that the as-cast microstructure of the alloy with no Y addition consisted of alpha-Mg, Mg-Zn binary and Mg-Zn-Nd ternary phases. With increasing Y additions, the average grain size showed a substantial decrease and two kinds of ternary Mg-Zn-Y ternary phases, designated as I-phase (Mg3Zn6Y) and W-phase (Mg3Zn3Y2) were formed. Homogenization treatment resulted in a partial dissolution of second phase particles. Extrusion process gave rise to a remarkable grain refinement due to the DRX mechanism. The extruded alloys with no Y addition exhibited poor corrosion resistance due to the strong micro galvanic coupling effect. Y additions up to 1 wt% improved the corrosion resistance due to the formation of finer grains, fine and uniform distribution of second phase particles and more stable oxide film. (c) 2020 Published by Elsevier B.V. on behalf of Chongqing University.
Effect of Zn addition on mechanical and corrosion properties of as-cast and as-extruded WE43 magnesium alloys
(Iop Publishing Ltd, 2019) Subasi, Yasin; Turen, Yunus; Zengin, Huseyin; Ahlatci, Hayrettin; Sun, Yavuz
In this study, the microstructure, mechanical properties and corrosion resistance of as-cast and as-extruded WE43-xZn (x;=;0, 0.5, 1.0 wt%) magnesium alloys were investigated. The microstructure of the as-cast alloys showed that the WE43-xZn alloys contained Mg41Nd5 and Mg24Y5 intermetallic compounds. Besides, LPSO (Long-period stacking ordered) type Zn-rich phases were also originated in the microstructure with increasing Zn content. Furthermore, LPSO structure was observed both in the ?-Mg grain and at the grain boundaries in Zn-containing WE43 alloys. The Vickers hardness values increased by the raising Zn content in the as-cast, solution treated and as-extruded WE43-xZn alloys. It was observed that yield strength (YS) increased gradually by the addition of Zn content, but 0.5 wt% Zn addition to as-cast WE43 alloy resulted in much more improvements on the ultimate tensile strength (UTS) and elongation % (EL) values compared to as-cast WE43-1.0Zn alloy. It was seen that mechanical properties improved with increasing Zn content for the as-extruded alloys. The as-cast specimens showed that corrosion resistance improved by increasing Zn content due to the presence of LPSO structures, but in the extruded alloys it varied in relation to the presence and distribution of second phases and also the morfologies of LPSO structures.
Effects of alloying element and cooling rate on properties of AM60 Mg alloy
(Iop Publishing Ltd, 2019) Elen, Levent; Cicek, Bunyamin; Koc, Erkan; Turen, Yunus; Sun, Yavuz; Ahlatci, Hayrettin
Magnesium and its alloys have become important structural materials in the last couple of decades due to their exceptional and mechanical properties. In this study, the effects of the introduction Cd, Bi, and Sn alloying elements were introduced into AM60 alloys produced from Mg-Al-Mn triple junction in order to improve the microstructural and mechanical properties. The weight percent of the alloying elements was chosen as 0.5% wt besides the introduction of the additional alloying elements, the effect of cooling rate on microstructural and mechanical properties of the alloys have been investigated. The results showed that the alloying elements introduced to AM60 resulted in an improvement in the mechanical properties of the alloys, which is attributed to the changes in the microstructure. The higher cooling rate led to the formation of the finer a-Mg master matrix which in turn enhanced the mechanical properties of the alloys. It was observed that the intermetallic phase of beta-Mg17Al12 at the grain boundaries became thinner due to the rapid cooling rate and the introduction of the alloying elements, and the continuity decreased and the intergranular distance shortened. The addition of the alloying element increased the tensile strength of the AM60 alloy from 140 MPa to 210 MPa and the elongation values increased from 5% to 22%. The effects of the alloying elements and the cooling rate on the hardness and yields properties of the samples were also studied.
EFFECTS OF BISMUTH (BI) ADDITIONS ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF AZ91 ALLOY
(Tanger Ltd, 2015) Elen, Levent; Zengin, Huseyin; Turen, Yunus; Turan, Muhammet Emre; Sun, Yavuz; Ahlatci, Hayrettin
In this study, the effects of bismuth additions of 0.2, 0.5 and 1 wt% on microstructure and mechanical properties of AZ91 alloy were examined. A permanent mold casting procedure was carried out to produce the alloy billets under a mixed gas atmosphere of SF6 and CO2. Microstructural investigations showed that Mg3Bi2 intermetallic phases were formed in all the samples and it coarsened with increasing amount of Bi in AZ91 alloy. Furthermore, a finer dispersion of Mg17Al12 intermetallic phases was observed in the structures as the amount of Bi in AZ91 increased. It was also showed that increasing Bi addition increased the hardness of AZ91 alloy. However, the highest hardness value was found for the alloy having 0.5wt% Bi addition that means high amount of Bi can decrease the hardness of AZ91 alloy. On the other, there were no considerable changes in the tensile strengths and yield strengths of the alloys as the amount of Bi increased although a slight increase in both strengths were observed with increasing amount of Bi. Percent elongation at break showed a decrease as Bi addition increased.
Effects of carbonaceous reinforcements on microstructure and corrosion properties of magnesium matrix composites
(Elsevier Science Sa, 2018) Turan, Muhammet Emre; Sun, Yavuz; Aydin, Fatih; Zengin, Huseyin; Turen, Yunus; Ahlatci, Hayrettin
In this study carbonaceous (C-based) reinforced AZ91 matrix composites were fabricated with the same weight fraction of 0.50 wt.% via semi powder metallurgy. The hot pressing test machine was used under high purity argon atmosphere. Multi-wall carbon nanotube (MWCNT), Graphene Nanoplatelets (GNPs) and Fullerene (C60) were used as reinforcements. Microstructure, hardness and corrosion performances of fabricated composites were investigated. Results show that hardness of AZ91 alloy was improved with the addition of carbonaceous reinforcements. AZ91/C60 composite exhibited highest hardness performance. However, corrosion performance of AZ91 was affected negatively by the addition of reinforcements. MWCNT exhibited highest corrosion rate among the fabricated samples.
Effects of Zn, Nd, and Ca addition on the microstructure, mechanical and corrosion properties of biodegradable Mg-Ag alloys
(Edp Sciences S A, 2023) Turen, Yunus; Elen, Levent
In this study, casting, extrusion, biocorrosion and corrosive wear properties of 0.5 wt.% (Zn, Ca, and Nd) element added Mg-3%Ag alloys were investigated. As a result of the experimental studies, it was observed that the grains in the Zn and Ca added as-cast alloys became thinner, and thus the mechanical properties of the investigated alloys such as yield strength and hardness were improved. At the same time, the applied extrusion process provided an increase in the mechanical properties by refining the grain structure of the investigated alloys. As a result of in vitro tests, larger pitting was observed in as-cast alloys, while smaller and shallower corrosion pits were observed in extruded alloys. In the corrosive wear tests, the wear rate of extruded alloys generally showed a decreasing trend. However, the composition of both as-cast and extruded Mg-3% Ag-0.5%Zn-0.5% Ca was the alloy that exhibited the lowest value in terms of the wear rate.

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