Yazar "Demirtas, Huseyin" seçeneğine göre listele

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    The effect of hot rolling process on macro-texture and high-temperature mechanical properties of AZ31B alloy modified by Ca and Ce
    (Sage Publications Ltd, 2023) Kara, Ismail Hakki; Demirtas, Huseyin
    This study examines the high-temperature tensile properties of AZ31 and AZ31-1.0Ca-0.2Ce alloys in different rolling directions. Tensile test results at 250 degrees C showed that the ductility of AZ31-1.0Ca-0.2Ce alloy increased threefold in the 90 degrees perpendicular direction to rolling direction. Moreover, both strength and elongation values of AZ31-1.0Ca-0.2Ce alloy were higher than those of AZ31. Macro-texture measurements revealed that AZ31 and AZ31-1.0Ca-0.2Ce alloys showed strong and weakened basal texture in the rolling direction, respectively. The combined effect of secondary phases and texture weakening increased the high-temperature ductility (49%) of AZ31-1.0Ca-0.2Ce. In the rolling direction, yield (YS) and ultimate tensile strength of AZ31-1.0Ca-0.2Ce were obtained as 115 and 121 MPa, respectively. These values were higher than AZ31 alloy due to the stronger texture of the non-basal planes. The fracture surface of AZ31 samples proved that the rough and crack-dominated surface led to brittle fracture formation. However, fine-sized dimples resulted in a ductile fracture in AZ31-1.0Ca-0.2Ce samples.
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    The effect of porosity on the mechanical properties of Ti-8Nb-8Zr-8Cu alloy
    (Taylor & Francis Ltd, 2022) Demirtas, Huseyin
    The present study investigated the mechanical performance of Ti-8Nb-8Zr-8Cu (at.-%) alloys containing different porosity levels. Metallographic examination and phase analysis of samples was performed by scanning electron microscope (SEM), optical microscopy (OM), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD) measurements. The mechanical properties were detected by uniaxial compression test, micro and macro hardness measurements. The wear behaviour was determined by a dry wear test on the bulk sample. The ultimate compressive strength decreased from 1077.30 to 344.65 MPa with 50% porosity and the modulus of elasticity from 15.6 to 9.5 GPa. These values show that it may be suitable for bone replacement considering the stress shield effect.
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    Effect of Relative Density on Microstructure, Corrosion Resistance and Mechanical Performance of Porous Ti-20Zr Alloys Fabricated by Powder Metallurgy
    (Springer Heidelberg, 2024) Karakurt, Eyyup Murat; Huang, Yan; Kaya, Mehmet; Demirtas, Huseyin; Acikgoz, Abuzer; Demircan, Gokhan
    The microstructure, corrosion resistance and mechanical properties of a binary Ti-20Zr (at. %) alloy with differing porosities were investigated. The alloys were produced following a standard powder metallurgy with sintering at 1200 degrees C for 4, 6, and 8 h. A space holder agent was used to obtain two ranges of relative density, i.e., 74.8-89.3% and 54.6-66.7%. Metallographic examinations were conducted by using optical microscopy and scanning electron microscopy. The confirmation of chemical composition was performed by energy dispersive spectrometry and elemental mapping analysis. Electron backscatter diffraction analysis was conducted to investigate microstructure morphology. Phase identifications were detected by X-ray diffraction. Uniaxial compressive tests were carried out and also potentiodynamic polarization was employed to understand the corrosion performances of the alloys. Experimental results showed that the pore size and pore connectivity were able to be controlled by the sintering time and a fixed amount of space holder agent. The phase constituents of the alloys were characterized as a mixture of predominant hcp alpha phase and some distorted hcp alpha ' phase. As foreseen, the ultimate compressive strength and elastic modulus of the alloys increased with increasing relative density. Results of corrosion resistance revealed adding space holder reduced the polarization resistance of Ti-20Zr (at. %) sintered for 6 h from 15.4 to 14.09 omega. However, volume fraction of general porosity did not affect the microstructure of the alloys. In conclusion, the relative density of the alloys achieved in this study played a crucial role on the mechanical properties and corrosion properties.
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    MECHANICAL AND WEAR PROPERTIES OF HIGH RATE NIAL PARTICLE-REINFORCED AL COMPOSITES PRODUCED BY PRESSURE INFILTRATION METHOD
    (Springer Int Publ Ag, 2021) Demirtas, Huseyin; Yildiz, Ramazan; Cevik, Engin
    In this study, Al matrix composites reinforced by the high amount of NiAl (40%) were produced by the pressure infiltration method. Commercially AA1050 (99.59 %) was used as matrix material and NiAl (at. 1:1) particles were used as reinforcement. Also, a small amount of Mo (wt. 2%) was added into NiAl for a better matrix-particle interface and to increase the mechanical properties. The proportion of particles was kept constant, and their sizes were changed from 45 to 125 mu m. The microstructures were examined by SEM, and formed phases were determined by EDS and XRD analysis. Mechanical properties and wear behavior were determined by compression, hardness, and abrasion tests. As a result of these tests, it was determined that composites were produced successfully. It was determined that compressive strength increased with decreasing particle size. And also, small particle size composites showed higher wear resistance.
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    Mechanical characterisation of laminated composite AISI 430/304 stainless steels with 1050 Al alloy interlayer Caracterisation mecanique des aciers inoxydables composites lamines AISI 430/304 avec couche intermediaire d'alliage d'Al 1050
    (Taylor & Francis Ltd, 2023) Demirtas, Huseyin; Incesu, Alper; Atay, Gokhan
    In this study, multilayered metal composites of austenitic stainless steel (AISI 304) / aluminum alloy (AA 1050) / ferritic stainless steel (AISI 430) are investigated in rolled and heat-treated (350C for 24 h) forms comparatively. SEM analysis, tensile test, peel test, bending test, and Vickers microhardness measurement were applied to reveal the microstructural characterisation and mechanical properties of composites. The presence of Fe2Al5 and Fe4Al13 phases are detected in the microstructure investigations, however, significantly thick intermetallic phases were not observed at the interfaces of the laminates. Tensile test results show no significant change in strength despite the increase in ductility after heat treatment. The highest strength of 329.4 MPa and the highest elongation of 26.1% is obtained from the heat-treated condition. The highest interface bond strength is observed at AA1050 / AISI 430 interface after heat treatment. No separation is observed between the layers after bending to a 60 angle. A decrease is observed in the hardness values of all layers with the heat treatment. Thus, it has been demonstrated how significant the heat treatment temperature and time, as well as the rolling temperature, are for better interface interaction and mechanical properties for layered composites.
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    Microstructural, Biomechanical, and In Vitro Studies of Ti-Nb-Zr Alloys Fabricated by Powder Metallurgy
    (Mdpi, 2023) Karakurt, Eyyup Murat; Cetin, Yuksel; Incesu, Alper; Demirtas, Huseyin; Kaya, Mehmet; Yildizhan, Yasemin; Tosun, Merve
    This study investigated the microstructures, mechanical performances, corrosion resistances, and in vitro studies of porous Ti-xNb-10Zr (x: 10 and 20; at. %) alloys. The alloys were fabricated by powder metallurgy with two categories of porosities, i.e., 21-25% and 50-56%, respectively. The space holder technique was employed to generate the high porosities. Microstructural analysis was performed by using various methods including scanning electron microscopy, energy dispersive spectroscopy, electron backscatter diffraction, and x-ray diffraction. Corrosion resistance was assessed via electrochemical polarisation tests, while mechanical behavior was determined by uniaxial compressive tests. In vitro studies, such as cell viability and proliferation, adhesion potential, and genotoxicity, were examined by performing an MTT assay, fibronectin adsorption, and plasmid-DNA interaction assay. Experimental results showed that the alloys had a dual-phase microstructure composed of finely dispersed acicular hcp & alpha;-Ti needles in the bcc & beta;-Ti matrix. The ultimate compressive strength ranged from 1019 MPa to 767 MPa for alloys with 21-25% porosities and from 173 MPa to 78 MPa for alloys with 50-56% porosities. Noted that adding a space holder agent played a more critical role in the mechanical behaviors of the alloys compared to adding niobium. The pores were largely open and exhibited irregular shapes, with uniform size distribution, allowing for cell ingrowth. Histological analysis showed that the alloys studied met the biocompatibility criteria required for orthopaedic biomaterial use.
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    Production and characterization of in-situ Al-NbB2 composites
    (Elsevier, 2023) Demirtas, Huseyin; Karakulak, Erdem; Nadendla, Hari Babu
    We report here a melt processing route for the production of Al-NbB2 and Al-Cu-NbB2 in-situ composites in which fine NbB2 particles are uniformly distributed in Al matrix. During solidification, in-situ formed NbB2 phase in liquid Al contributed for enhanced heterogeneous nucleation, which caused a dramatic refinement of primary Al grain size, uniformly distributed second phases and enhanced wear characteristics.
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    Properties of Al2O3 particle reinforced composites coating on IF steel
    (Taylor & Francis Ltd, 2022) Demirtas, Huseyin; Cug, Harun; Elkilani, Rajab
    In this study, IF steel was coated by the low-pressure cold spray deposit method with different coating materials. Al, Ni, Zn, and Sn powders were used as coating matrix. All coating materials were reinforced by Al2O3 particles. Mechanical properties of the coatings were determined by three-point bending, scratch, wear tests, and hardness measurement. Micro-level defects and structure of coatings were examined by SEM, EDX, and Optical microscope analysis. All coatings were applied successfully, and the most distinct defects occurred in the Ni-matrix coating. The hardness of the Ni matrix coating was the highest, however the wear resistance was the highest for the Zn matrix coating. The lowest hardness and wear resistance were measured in the Sn matrix coating. As a result of the bending test, distinct crack formations were observed in the Zn matrix coating, unlike the others.
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    Understanding the effect of Ni content on microstructure and mechanical properties of A384 HPDC alloy
    (Elsevier Science Sa, 2022) Demirtas, Huseyin; Karakulak, Erdem; Babu, Nadendla Hari
    Investigations have been carried out to understand the correlation between Ni content and properties of HPDC cast A384 aluminium alloy in as-cast and heat-treated conditions. Depending on Ni content in the alloy, different Ni-bearing intermetallics were formed. Suitable heat treatment conditions were selected after a series of experiments to obtain optimal mechanical properties. Most of the Ni containing inter-metallics found to be stable at solutionizing temperatures which have a dramatic effect on the mechanical properties of alloys after natural and artificial aging. The results showed that, after heat treatment, to achieve higher strength values lower Ni additions are favourable. (c) 2021 Published by Elsevier B.V.