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Öğe Auto-detection of intermetallic and eutectic phases in microstructure of the az91 mg-alloys by image processing techniques(2022) Elen, Abdullah; Elen, LeventAZ91, which is used in the production of parts in the aerospace, defense and automotive industries, can be enhanced by the addition of an alloying element or the cooling rate, due to the weak strength and formability properties of advanced technology Mg-alloys. The microstructure change in Mg alloys significantly affects the mechanical properties. By analyzing the microstructure of these alloys, a close estimate of the mechanical properties can be made. In this study, an image processing-based model is proposed that automatically recognizes the intermetallic and eutectic phases required for the analysis of microstructural properties in AZ91 Mg-alloys. The proposed method consists of two stages; In the first step, the eutectic phase template is obtained as a binary image. In the second step, the binary image containing the intermetallic and eutectic phases is obtained and the result image with only the intermetallic phases is obtained by taking the difference of these two patterns. Experimental studies have shown that the proposed method gives a result close to the real value in the detection of eutectic phases.Öğe AZ91 magnezyum alaşımına farklı oranlarda Bi ve Sb ilavesi ile katılaşma hızının mikroyapı ve mekanik özelliklere etkisi(Karabük Üniversitesi, 2012) Elen, Levent; Türen, YunusBu çalışmada, AZ91 magnezyum alaşımının mikroyapı ve mekanik ve özelliklerini geliştirmek için alaşımlara %0,2-%0,5 ve %1 oranlarında Bizmut (Bi) ve Antimon (Sb) elementleri ilave edilmiştir. AZ91 serisi alaşımlar dört farklı soğuma hızına sahip kademeli kalıba dökülmüştür.Sonuçlar; Soğuma hızının artması ile AZ91 alaşımlarının tane yapısının küçüldüğünü ve oluşan intermetalik (Mg17Al12) fazın incelerek parçalandığını göstermiştir. Mikroyapıdaki bu değişikliklere paralel olarak alaşımların çekme, akma ve % uzama oranları artmıştır. AZ91 magnezyum alaşımına Sb ilaveleri alaşımın mekanik dayanımını arttırmıştır. Fakat Bi ilavesi mekanik özelliklerde kayda değer bir değişiklik göstermemiştir.Öğe Az91 mg alaşımına farklı oranlarda sb ilavesi ile katılaşma hızının mikroyapı ve mekanik özelliklere etkisi(2019) Elen, Levent; Türen, Yunus; Koç, ErkanMevcut kullanım alanları gün geçtikçe artış gösteren Mg alaşımlarının, teknolojik gelişmelere uyum sağlayabilmesi içinmekanik özellikler bakımından daha fazla geliştirilmesi gerekliliği ortaya çıkmıştır. Günümüzde çözünebilir biyo-malzemeolarak sağlık alanında da kullanılmaya başlayan Mg ve alaşımlarına kazandırılan fiziksel ve mekanik özellikler malzemeninkullanım ömrünü tayin etmektedir. Dolayısıyla bu çalışmada, AZ91 serisi Mg alaşımına farklı oranlarda (%0.2 - %0.5 ve %1.0)Sb elementi ilavesi ve katılaşma hızının da etkisiyle mekanik özelliklerinin geliştirilmesi amaçlanmıştır. Yapılan çalışmanınneticesinde sonuçlar incelendiğinde; AZ91 alaşımının genel olarak tane yapısının ?-Mg ve tane sınırları boyunca yayılan ?-Mg17Al12 fazından oluştuğu saptanmıştır. Hızlı soğumanın tane yapısında küçülmelere sebep olduğu bununla birlikte tanesınırlarında bulunan Mg17Al12 intermetalik fazının incelip parçalandığı tespit edilmiştir. Tespit edilen bu etkilerin neticesinde dealaşımın çekme, akma ve uzama değerlerinde artışın olduğu gözlenmiştir. Bununla birlikte AZ91 alaşımına ilave edilen Sb ileyapıda Mg3Sb2 fazı oluşmuştur. Bu intermetalik fazın yapıda meydana getirdiği değişiklikler ile alaşımın mekanik özelliklerindeartış izlenmiştir. AZ91 alaşımının çekme dayanımı Sb ilavesi ile 163 MPa seviyelerinden 217 MPa seviyelerine kadariyileşmiştir. Sb ilavesiyle AZ91 alaşımında sertlik değerleri yaklaşık 57 HV değerlerinden 81 HV değerlerine yükselmiştir.Öğe 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, BunyaminThis 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.Öğe Biyobozunur mg-ag alaşımlarının mikroyapı, mekanik ve korozyon özelliklerine zn ve nd elementlerinin etkisi(2022) Elen, LeventBu çalışmada, %0,5 oranlarında (Zn ve Nd) element ilaveli Mg-%3Ag döküm alaşımlarının, mikroyapı, mekanik, in vitro korozyon özellikleri incelenmiştir. Deney sonuçlarına göre, alaşımlara ilave edilen Zn elementinin etkisiyle (Mg-3Ag-0,5Zn) alaşımda tanelerin inceldiği ve bu sayede alaşımların bazı mekanik özelliklerinin de arttığı gözlenmiştir. Nd elementi ilavesi ile oluşturulan (Mg-3Ag-0,5Nd) alaşımında ise en yüksek sertlik değeri gözlenmiştir. Korozyon testleri sonrasında ise alaşım elementlerine bağlı olarak farklı korozyon değerleri tespit edilmiştir. Alaşımların yapısında tespit edilen ikincil fazların, alaşımların mekanik özelliklerine ve korozyon özelliklerine etki ettiği tespit edilmiştir. Tüm bu sonuçlar neticesinde Mg-Ag alaşımlarının biyomalzeme alanında gelişime açık ve ihtiyaç duyduğu kanısına varılmıştır.Öğe Biyobozunur mg-ag döküm alaşımlarının mikroyapı mekanik ve in vitro korozyon özelliklerinin incelenmesi(2022) Elen, Levent; Türen, Yunus; Ahlatcı, Hayrettin; Ünal, MehmetBu çalışmada, magnezyuma %1 ve %3 oranlarında gümüş ilave edilmiş Mg-Ag alaşımlarının döküm sonrası mekanik ve in vitro korozyon özellikleri incelenmiştir. Deney sonuçlarına göre, döküm alaşımlarındaki ilave edilen Ag’nin miktarı arttıkça yapıda ortaya çıkan ikincil fazlar (Mg4Ag ve Mg54Ag17) daha belirginleşmiştir. Ayrıca Ag miktarı arttıkça, döküm yapısına kıyasla tanelerin inceldiği ve bu sayede alaşımların mekanik özellikleri de artmıştır. Potansiyodinamik polarizasyon testlerinde ise Ag miktarına bağlı olarak, alaşımların korozyon akım yoğunlukları artış göstermiştir.Hank sıvısı ile yapılan testler sonucunda ise Mg-1Ag alaşımının korozyonu daha hızlı ilerlediği ve buna bağlı olarak da Mg-1Ag alaşımında daha fazla kütle kaybının olduğu tespit edilmiştir. Tüm bu sonuçlar ışığında bakıldığında, Mg-Ag alaşımlarında Ag ilavesi ile deney sonuçlarının değişim göstermesi, Mg-Ag alaşımlarının gelişime açık olduğunu ve biyomalzeme olarak hayatımıza girmeye büyük bir aday olduğunu ortaya koymuştur.Öğe A Comparative Study on Microstructure, Mechanical and Tribological Properties of A4, AE41, AS41 and AJ41 Magnesium Alloys(Springer, 2019) Zengin, Huseyin; Turen, Yunus; Elen, LeventMicrostructure, 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.Öğe 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, ErkanMagnesium 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.Öğe Effect of cooling rate on microstructure, mechanical and wear properties of Mg-2Zn and Mg-2Zn-1Mn alloys(Taylor & Francis Ltd, 2024) Elen, Levent; Elen, Nurhan CevikIn this study, the wear characteristics of Mg-2Zn and Mg2Zn-1Mn alloys in both dry and corrosive conditions, as well as their mechanical properties dependent on cooling rate, were examined. It has been determined that MgZn, Mg2Zn3 and MgZn2 phases are formed together with the alpha-Mg main matrix in the microstructure of the alloys. The highest tensile strength (188.6 MPa) was observed in section B of Mg-2Zn alloy. With this, section A of the Mg-2Zn-1Mn alloy showed the lowest wear value (0.00144 mm3/N.m) following dry wear. However, under corrosive wear conditions, the lowest wear rate (0.0008 mm3/N.m) was exhibited at B section in Mg-2Zn-1Mn alloy. In the SEM images of the abrasive tips used in the wear tests, it was determined that the scratches occurred along the wear direction, and as a result of the EDX analysis, alloying elements were transferred from the alloys to the abrasive tip. Dans cette etude, on a examine les caracteristiques d'usure des alliages Mg-2Zn et Mg-2Zn-1Mn dans des conditions seches et corrosives, ainsi que leurs proprietes mecaniques dependantes de la vitesse de refroidissement. On a determine que les phases MgZn, Mg2Zn3 et MgZN2 se forment ensemble avec la matrice principale Mg-alpha dans la microstructure des alliages. Les sections C des deux alliages montraient les valeurs de durete maximales, qui resultaient de la vitesse de refroidissement. Cependant, on a observe la resistance a la traction la plus elevee (188.6 MPa) dans la section B de l'alliage Mg-2Zn. Avec cela, on a observe la limite d'elasticite la plus elevee (69.7 MPa) dans la section A de l'alliage Mg-2Zn-1Mn. En meme temps, la section A de l'alliage Mg-2Zn-1Mn montrait la valeur d'usure la plus faible (0.00144 mm3/N center dot m) apres usure par voie seche. Cependant, dans des conditions d'usure corrosives, la section B de l'alliage Mg-2Zn-1Mn exhibait le taux d'usure le plus faible (0.0008 mm3/N center dot m). Dans les images du MEB des pointes abrasives utilisees lors des essais d'usure, on a determine que les rayures se produisaient dans le sens de l'usure et, a la suite de l'analyse EDX, les elements d'alliage etaient transferes des alliages vers la pointe abrasive.Öğe 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. NajahThe 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%.Öğe 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, HayrettinMagnesium 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.Öğe 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, HayrettinIn 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.Öğe 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, LeventIn 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.Öğe Investigation of A New Type of Aluminum-Magnesium Alloy with Bismuth Additions Subjected to Thermomechanical Heat Treatment(Springer Int Publ Ag, 2024) Kilinc, Medine; Elen, Levent; Ahlatci, Hayrettin; Sun, Yavuz; Tueren, Yunus; Acarer, MustafaIn this study, the changes in microstructure, hardness, corrosion and wear properties of Al-Mg with 3% Mg content and new type Al-Mg-Bi alloys with 1.3% Bi addition were investigated with the application of thermomechanical process on the aging heat treatment characteristics. As a result of the applied thermomechanical process, a finer grained structure was obtained and a higher hardness value was achieved compared to the casting alloys. Bright phases in SEM micrographs were detected as (rod-shaped) intermetallic (Al6Mn) particles in TEM analyses. Additionally, it was determined that the independent dark particles in the Al matrix were Mg2Si phases. Both alloys showed evidence of the Al3Mg2 phase. However, corrosion tests have shown that the Al-Mg-Bi1.3 alloys with the addition of bismuth have higher corrosion resistance than the Al-Mg alloys. The Al-Mg-Bi1.3 alloys also exhibited improved wear resistance in dry and corrosive wear tests. While the wear of the investigated alloys in a dry environment is associated with an improvement in hardness, wear resistance in corrosive media is improved by the addition of Bi, which reduces the formation of certain phases.Öğe Investigation of in-vitro biocompatibility and in-vivo biodegradability of AM series Mg alloys(Taylor & Francis Ltd, 2022) Comba, Arzu; Cicek, Bunyamin; Comba, Bahat; Sancak, Tunahan; Akveran, Gonul Arslan; Sun, Yavuz; Elen, LeventIn this study, in vitro/vivo biocompatibility experiments of Mg-Al-Mn alloy were carried out, and AM50 and AM60 alloys were used in the experiments. Immersion and potentiodynamic corrosion have been applied to these alloys in vitro. For biocompatibility, cytotoxicity test was performed. A total of 40 rats were used for the in-vivo experiment. AM series alloys were surgically placed in the femoral condyle as mini screws and monitored radiographically. AM alloys were removed together with the femur at the end of 7 weeks and further examined. After in-vivo application, the biodegradability level was successfully concluded with blood mineral analysis and urinalysis. In this study, the bioprocess of AM series Mg alloys with Al and Mn additions has been completed. As a result, the AM alloys used can be classified as biocompatible and biodegradable materials.Öğe Investigation of Intermetallic Phase Fractions and Dry-corrosive Wear Properties in Mg-Al-Si Ternary Alloy(Springer Int Publ Ag, 2024) Cicek, Bunyamin; Elen, Levent; Koc, Erkan; Saud, A. Najah; Sun, YavuzThis study produced a non-standard alloy of 85% Mg, 13.5% Al, and 1.5% Si by weight. In-depth microstructural, chemical, and morphological analyses of the secondary beta phases formed in the MgAlSi alloy were conducted. The formation processes of the intermetallic phases were also examined. Image processing was applied to the obtained microstructures using the Image-J program. The average alloy had a matrix alpha phase to secondary beta phase ratio of approximately 60/40. Furthermore, a dry and corrosive wear test were applied to the MgAlSi alloy by means of reciprocating motion. The wear rate was calculated to be at least 0.00137 mm(3)/Nm, indicating that the unique MgAlSi ternary alloy produced had very high wear resistance due to the presence of intermetallic phases.Öğe INVESTIGATION OF MICROSTRUCTURE, MECHANICAL AND CORROSION PROPERTIES OF BIODEGRADABLE Mg-Ag ALLOYS(Polska Akad Nauk, Polish Acad Sciences, Inst Metall & Mater Sci Pas, 2022) Elen, Levent; Turen, Yunus; Ahlatci, Hayrettin; Sun, Yavuz; Unal, MehmetIn this study, microstructure, mechanical, corrosion and corrosive wear properties of Mg-xAg the as-cast and extruded alloys (x: 1, 3 and 5 wt. %Ag) were investigated. According to the experimental results, as the amount of Ag added in the casting alloys increases, the secondary phases (Mg4Ag, Mg54Ag17) emerging in the structure have become more clarified. Furthermore, it was observed that as the amount of Ag increased, the grain size decreased and thus the mechanical properties of the alloys increased. Similarly, the extrusion process enabled the grains to be refined and the mechanical properties to be increased. As a result of the in vitro tests performed, the Mg-1Ag exhibited very bad corrosion properties compared to other alloys. On the other hand, according to corrosive wear tests results, a high wear rate and friction coefficient were found for Mg-5Ag alloys.Öğe Mg-Ag ALAŞIMLARININ MEKANİK VE BİYOÇÖZÜNEBİLİRLİK ÖZELLİKLERİNE İLAVE ELEMENTLERİN ETKİSİNİN İNCELENMESİ(2021-09) Elen, LeventBu çalışmada, Mg-Ag alaşımlarının döküm, ekstrüzyon, mikroyapı, tekstür, mekanik, korozyon ve korozif aşınma özellikleri incelenmiştir. Çalışma, farklı oranlarda Ag ilaveli (%1, %3 ve %5) Mg-Ag alaşımları ve %3 Ag içeren Mg-Ag alaşımına %0,5 oranlarında (Zn, Ca ve Nd) element ilave edilerek oluşturulan Mg-Ag alaşımları olmak üzere iki grup şeklinde gerçekleştirilmiştir. Alaşımların ergitimi kapalı sistem indüksiyon ocağında koruyucu gaz (Ar) kullanılmıştır ve dökümler ise koruyucu gaz (CO2+%1SF6) altında yapılmıştır. Döküm sonrası yapılan ekstrüzyon işlemi ise hidrolik pres altında 16:1 ekstrüzyon oranında, 0,3 mm/s hızında ve 300 °C’de gerçekleştirilmiştir. Ekstrüzyon öncesi numunelere 430 °C’de 16 saat boyunca homojenleştirme ısıl işlemi uygulanmıştır. Döküm ve ekstrüzyon sonrası numunelerin mikroyapı, tekstür, çekme, aşınma ve korozyon testleri yapılmıştır. Korozyon testleri Hank sıvısı içerisinde ve ~37 °C’de gerçekleştirilmiştir. Korozif aşınma testleri ise Hank sıvısı içerisinde oda sıcaklığında, İleri-geri aşınma metodu ile 400 metrelik aşınma mesafesi ve 20 N’luk yük uygulanarak gerçekleştirilmiştir. Deney sonuçlarına göre, döküm alaşımlarındaki ilave edilen Ag’nin miktarı arttıkça yapıda ortaya çıkan ikincil fazlar (Mg4Ag ve Mg54Ag17) daha belirginleşmiş ve taneler incelmiştir. Ayrıca ekstrüzyon işlemi de tanelerin incelmesine ve mekanik özelliklerin artmasına yardımcı olmuştur. %0,5 oranlarında (Zn, Ca ve Nd) element ilaveli Mg-3Ag alaşımlarının deney sonuçlarına göre, döküm alaşımlarındaki ilave edilen Zn ve Ca elementlerinin etkisiyle tanelerin inceldiği ve bu sayede alaşımların bazı mekanik özelliklerinin de arttığı gözlenmiştir. Benzer şekilde ekstrüzyon işlemi de tanelerin incelmesine ve buna bağlı olarak mekanik özelliklerin artmasında etkili olmuştur. Yapılan in vitro testler sonucunda ise Mg-5Ag alaşımı daha iyi korozyon özellikleri sergilemiştir. Mg-1Ag ise diğer alaşımlara kıyasla oldukça kötü korozyon özelliği sergilemiştir. %0,5 oranlarında (Zn, Ca ve Nd) element ilaveli Mg-3Ag döküm alaşımlarında çok farklı sonuçlar elde edilmezken ekstrüzyon alaşımlarda bu durum daha belirgin hale gelmiş ve daha homojen korozyon özellikleri sergilemiştir. Potansiyodinamik testlerinde ekstrüzyon numunelerinin döküm numunelerine kıyasla korozyon akım yoğunlukları artış göstermiş ancak korozyon potansiyelleri düşüş sergilemiştir. Ancak alaşım elementlerinin ikli kombinasyonlar halinde ilave edilerek oluşturulan alaşımlarda (Mg-3Ag-0,5Zn-0,5Nd, Mg-3Ag-0,5Zn-0,5Ca, Mg-3Ag-0,5Nd-0,5Ca ve Mg-3Ag-0,5Zn-0,5Nd-0,5Ca) durum tam tersine dönmüştür. Daldırma korozyon testi sonrası ortalama korozyon hızı genel olarak ekstrüzyon ürünlerinde daha fazla görülürken ikili ve üçlü alaşım elementi kombine edilmiş Mg-Ag alaşımlarında (Mg-3Ag-0,5Zn-0,5Nd, Mg-3Ag-0,5Zn-0,5Ca, Mg-3Ag-0,5Nd-0,5Ca ve Mg-3Ag-0,5Zn-0,5Nd-0,5Ca) ise, 1 günlük daldırma sonrası ekstrüzyon alaşımları daha yüksek değer sergilerken 3 günlük daldırma sonrası döküm alaşımları daha yüksek değer sergilemiştir. Korozif aşınma testlerinde ise en düşük aşınma hızı hem döküm hem de ekstrüzyon (Mg-3Ag-0,5Zn-0,5Nd, Mg-3Ag-0,5Zn-0,5Ca ve Mg-3Ag-0,5Zn-0,5Nd) alaşımlarında tespit edilmiştir. Korozif aşınma testlerinde ise, Mg-5Ag alaşımında yüksek aşınma oranı ve sürtünme katsayısı ortaya çıkmıştır. Bununla birlikte Mg-3Ag hem mekanik ve aşınma hem de korozyon özellikleri bakımından %1 ve 5 Ag içeren alaşımlara kıyasla optimum özellikler sergilemiştir. %0,5 oranlarında (Zn, Ca ve Nd) element ilaveli Mg-3Ag alaşımların korozif aşınma testlerinde ise genel olarak ekstrüde alaşımlarda aşınma hızı ve ve miktarı düşüş eğilimi sergilemiştir. Ancak hem döküm hem de ekstrüde Mg-3Ag-0,5Ca alaşımı aşınma hızı ve miktarı bakımından en düşük değer sergileyen alaşım olmuştur.Öğe Microstructural, mechanical, and in vitro corrosion properties of biodegradable Mg-Ag alloys(Aip Publishing, 2022) Elen, Levent; Turen, Yunus; Ahlatci, Hayrettin; Unal, Mehmet; Ergin, DenizIn this study, casting, extrusion, biocorrosion, and corrosive wear properties of 0.5 wt. % (Zn, Ca, and Nd) element added Mg-3 wt. % Ag alloys were investigated. According to the test results, it was observed that the grain refinement occurred with the effect of Zn and Ca element additions in the as-cast alloys and thus some mechanical properties of the alloys improved. Similarly, the extrusion process provided grain refinement and improved mechanical properties. As a result of in vitro corrosion tests, similar results were also obtained in the as-cast alloys, while this situation became more apparent in the extruded alloys and exhibited more homogeneous corrosion properties. In the corrosive wear tests, the wear rate of the extruded alloys generally showed a decreasing trend. However, both the as-cast and extruded Mg-3 wt. %Ag-0.5 wt. % Ca alloys exhibited the lowest wear rate. Published under an exclusive license by the AVS.
